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                  AMENDED AND RESTATED STOCK PURCHASE AGREEMENT

                                  by and among


                                  SPIRENT PLC,
                                  SPIRENT B.V.,
                         SPIRENT INTERNATIONAL INC. and
                                  SPIRENT GMBH

                                       and

                            GENERAL ELECTRIC COMPANY


                         Dated as of September 10, 2001


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                                                            Amended and Restated
                                                        Stock Purchase Agreement

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                                TABLE OF CONTENTS

<Table>
<Caption>
                                                                                                  Page
                                                                                                  ----
<S>  <C>                                                                                            <C>
1.   Sale and Purchase...............................................................................1
     1.1      Sale and Purchase of the Shares........................................................1
     1.2      Closing................................................................................1
     1.3      [Reserved.]............................................................................2
     1.4      Consequences of Failure to Obtain Certain Consents.....................................2

2.   Representations and Warranties of the Sellers...................................................3
     2.1      Corporate Status and Authority of the Sellers..........................................3
     2.2      No Conflicts; Consents and Approvals, etc..............................................4
     2.3      Corporate Status of the Companies......................................................4
     2.4      Capitalization.........................................................................5
     2.5      Subsidiaries...........................................................................5
     2.6      Financial Statements...................................................................6
     2.7      Absence of Undisclosed Liabilities.....................................................6
     2.8      Real Property; Assets..................................................................6
     2.9      Contracts..............................................................................8
     2.10     Employment Agreements and Employee Plans etc...........................................9
     2.11     Intellectual Property.................................................................11
     2.12     Governmental Authorizations; Compliance with Law......................................12
     2.13     Litigation............................................................................12
     2.14     Taxes.................................................................................13
     2.15     Absence of Changes....................................................................13
     2.16     Environmental Matters.................................................................15
     2.17     Banking and Agency Arrangements.......................................................16
     2.18     Affiliate Transactions................................................................16
     2.19     Brokers...............................................................................16

3.   Representations and Warranties of the Purchaser................................................16
     3.1      Corporate Status and Authority........................................................16
     3.2      No Conflicts; Consents and Approvals, etc.............................................17
     3.3      Financial Ability to Perform..........................................................17
     3.4      Litigation............................................................................17
     3.5      Purchase for Investment...............................................................18
     3.6      Brokers...............................................................................18

4.   Covenants......................................................................................18
     4.1      Satisfaction of Closing Conditions....................................................18
     4.2      Conduct of Business, etc..............................................................18
     4.3      Access and Information................................................................19
     4.4      Taxes.................................................................................20
     4.5      Notifications; Supplements to Disclosures.............................................25
     4.6      Contact with Customers and Suppliers..................................................26
</Table>

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                                        i               Stock Purchase Agreement
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<Table>
<S>  <C>                                                                                            <C>
     4.7      Publicity.............................................................................26
     4.8      Intercompany Accounts.................................................................26
     4.9      Indemnification of Directors and Officers.............................................27
     4.10     Non-Competition.......................................................................27
     4.11     Insurance.............................................................................28
     4.12     Korean Joint Ventures.................................................................28
     4.13     German Assets; Taunton Lease..........................................................28
     4.14     Local Purchase Agreements.............................................................28
     4.15     Bank Accounts.........................................................................29
     4.16     Change of Name; Discontinuance of Use of "Spirent"....................................29
     4.17     Transitional Services.................................................................29

5.   Employees and Employee Benefit Plans...........................................................29
     5.1      Continuation of Benefits..............................................................29
     5.2      401(k) Plan...........................................................................30
     5.3      UK Pension Schemes....................................................................31
     5.4      Seller Retained Liabilities...........................................................31

6.   Conditions Precedent...........................................................................31
     6.1      General...............................................................................31
     6.2      Conditions to Obligations of Both Parties.............................................31
     6.3      Conditions to Obligations of the Sellers..............................................32
     6.4      Conditions to Obligations of the Purchaser............................................32

7.   Indemnification................................................................................33
     7.1      Survival of Representations and Warranties............................................33
     7.2      Indemnification.......................................................................33

8.   [Reserved.]....................................................................................38

9.   General Provisions.............................................................................38
     9.1      Modification; Waiver..................................................................38
     9.2      Entire Agreement......................................................................38
     9.3      Certain Limitations...................................................................38
     9.4      Termination...........................................................................39
     9.5      Expenses..............................................................................40
     9.6      Further Actions.......................................................................40
     9.7      Post-Closing Access...................................................................40
     9.8      Notices...............................................................................41
     9.9      Assignment............................................................................42
     9.10     No Third Party Beneficiaries..........................................................42
     9.11     Counterparts..........................................................................42
     9.12     Interpretation; Disclosure Schedules..................................................42
</Table>

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<Table>
<S>  <C>                                                                                            <C>
     9.13     Governing Law.........................................................................43
     9.14     Consent to Jurisdiction, etc..........................................................43
     9.15     Tax Treatment of Indemnity Payments...................................................44
     9.16     Waiver of Punitive and Other Damages and Jury Trial...................................44
     9.17     Certain Definitions...................................................................45
</Table>

Exhibit A     Wholly-Owned Companies

Exhibit B-1   Majority-Owned Companies

Exhibit B-2   Designated Receivables Jurisdictions

Exhibit C     Allocation of Purchase Price

Exhibit D     Financial Statements

Exhibit E     U.K. Pension Schemes

Exhibit F     Form of German Asset Purchase Agreement

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                                       iii              Stock Purchase Agreement
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                                  DEFINED TERMS

<Table>
<Caption>
Term                                                       Section
----                                                       -------
<S>                                                        <C>
Additional Transfer Agreements                             2.1

Affiliate                                                  9.17

Agreement                                                  Introduction

Ancillary Agreements                                       9.17

Applicable Percentage                                      9.17

Bond                                                       9.17

Business                                                   9.17

business day                                               9.17

Closing                                                    1.2

Closing Date                                               1.2

Code                                                       2.10(d)

Companies                                                  Recitals

Company                                                    Recitals

Company Employees                                          5.1(a)

Company Group                                              9.17

Confidentiality Agreement                                  4.3

control                                                    9.17

Damages                                                    7.2.1

Designated Receivables                                     Recitals

Dutch Asset Purchase Agreement                             9.17

Environmental Law                                          9.17

ERISA                                                      2.10(b)

Final Sale Date                                            1.4

Financial Statements                                       2.6

GAAP                                                       2.6

German Asset Purchase Agreement                            9.17

German Assets                                              2.8(d)

German Branch                                              9.17
</Table>

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                                       iv               Stock Purchase Agreement
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<Table>
<S>                                                        <C>
German Liabilities                                         9.17

Guaranty                                                   9.17

Guarantor                                                  8.1

Hazardous Substance                                        9.17

HSR Act                                                    2.2(b)

Indemnitee                                                 7.2.3

Indemnitor                                                 7.2.3

Intellectual Property                                      2.11

knowledge                                                  9.17

Leased Real Property                                       2.8(a)

Leases                                                     2.8(b)

Licenses                                                   2.11

Liens                                                      2.2(a)

Local Purchase Agreement                                   4.14

Material Adverse Effect                                    2.2(a)

Non-Company Affiliates                                     2.18

Organizational Documents                                   9.17

Owned Intellectual Property                                2.11

Owned Real Property                                        2.8(a)

Permitted Liens                                            2.8(a)

Person                                                     9.17

Plans                                                      2.10(b)

Purchase Price                                             1.1

Purchaser                                                  Introduction

Purchaser Indemnity                                        7.2.1

Purchaser 401(k) Plan                                      5.2

Recovery                                                   7.2.5

Reduced Taxes                                              4.4(d)

Schedule                                                   2

Schedules                                                  2
</Table>

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                                        v               Stock Purchase Agreement
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<Table>
<S>                                                        <C>
Seller 401(k) Plan                                         5.2

Sellers                                                    Introduction

Seller Indemnitees                                         7.2.2

Shares                                                     Recitals

Spirent B.V.                                               Introduction

Spirent GmbH                                               Introduction

Spirent International                                      Introduction

Spirent plc                                                Introduction

Straddle Period                                            4.4(b)

Straddle Return                                            4.4(c)

Subsidiary                                                 9.17

Taunton Lease                                              4.13(ii)

Taxes                                                      2.14

Tax Return                                                 2.14

Third Party Accountants                                    9.17

Unsold Company                                             1.4

U.S. Combined Income Taxes                                 9.17
</Table>

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                                       vi               Stock Purchase Agreement
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                                                                    EXHIBIT 4.11

          AMENDED AND RESTATED STOCK PURCHASE AGREEMENT (this "AGREEMENT"),
dated as of September 10, 2001, among SPIRENT plc, a company formed under the
laws of England and Wales ("SPIRENT PLC"), Spirent B.V., a Netherlands
corporation ("SPIRENT B.V."), Spirent International Inc., a Delaware corporation
("SPIRENT INTERNATIONAL"), and Spirent GmbH ("SPIRENT GmbH"), a German
corporation (collectively, the "SELLERS"), and General Electric Company, a New
York corporation (the "PURCHASER").

                              W I T N E S S E T H :

     WHEREAS, the parties hereto have entered into an agreement, dated September
7, 2001, and are amending and restating such agreement as set forth herein;

     WHEREAS, the Sellers own all of the outstanding capital stock of each of
the companies listed on Exhibit A hereto and a majority of the outstanding
capital stock of each of the companies listed on Exhibit B-1 hereto
(collectively, the "COMPANIES," and each individually, a "COMPANY");

     WHEREAS, on the Closing Date (as defined in Section 1.2), the Sellers and
certain Non-Company Affiliates (as defined in Section 2.18) may, at their
discretion, hold certain loans receivable (the "DESIGNATED RECEIVABLES") (i)
from certain of the Companies or their Subsidiaries organized in the
jurisdictions specified on Exhibit B-2 hereto or (ii) as otherwise identified on
Exhibit B-2; and

     WHEREAS, subject to the terms and conditions set forth herein, the Sellers
wish to sell, and the Purchaser wishes to purchase, all of the capital stock of
the Companies owned by the Sellers (in the aggregate or with respect to an
individual Company, the "SHARES"), and the Designated Receivables.

     NOW, THEREFORE, the parties hereto agree as follows:

          1. SALE AND PURCHASE.

          1.1  SALE AND PURCHASE OF THE SHARES. Subject to the terms and
conditions of this Agreement, at the Closing, the Sellers shall sell or cause to
be sold, and the Purchaser shall purchase, the Shares of each Company, the
German Assets and the Designated Receivables for an aggregate amount equal to
US$220,000,000 less the amount, if any, of indebtedness of the Companies or any
of their Subsidiaries under the facilities specified in items (f) - (j) of
Schedule 4.1 that is not converted to Designated Receivables and that will
remain outstanding following the Closing (such net amount, the "PURCHASE
PRICE").

          1.2  CLOSING. The closing of the sale and purchase of the Shares and
the Designated Receivables (the "CLOSING") will take place at Debevoise &
Plimpton, 919

                                                            Amended and Restated
                                                        Stock Purchase Agreement

<Page>

Third Avenue, New York, New York at 10:00 a.m. New York time, on November 8,
2001 or at such other date and time as the parties shall have agreed to in
writing. The date on which the Closing shall occur is hereinafter referred to as
the "CLOSING DATE." At the Closing:

          (a)  the Sellers shall deliver to the Purchaser stock certificates
     representing the Shares of all of the Companies, endorsed or accompanied by
     stock powers in favor of the Purchaser, or other evidence of transfer
     reasonably satisfactory to the Sellers and the Purchaser;

          (b)  the Sellers shall assign or cause to be assigned to the Purchaser
     the Designated Receivables, such assignments to be in form and substance
     reasonably satisfactory to the Sellers and the Purchaser; and

          (c)  the Purchaser shall deliver, by wire transfer of immediately
     available funds to a previously designated account of Spirent plc (on
     behalf of the Sellers), the Purchase Price.

          1.3  [Reserved.]

          1.4  CONSEQUENCES OF FAILURE TO OBTAIN CERTAIN CONSENTS.

          (a)  In the event that either of the consents described in items (b)
     and (c) of Schedule 6.2.2 have not been obtained by the Closing Date, then
     the receipt of each such consent shall be deemed not to constitute a
     condition to the Closing of the sale and purchase of the Shares of the
     Companies other than Thermometrics Technologies Limited and/or
     Thermometrics Japan Co. Limited (each, if the consent relating thereto has
     not been obtained by the Closing Date, an "UNSOLD COMPANY") and of the
     Designated Receivables, if any, associated with such Unsold Company, as the
     case may be. The parties shall nevertheless on the Closing Date consummate
     the purchase and sale of the Shares and the Designated Receivables other
     than the Shares of each Unsold Company and any Designated Receivables
     associated therewith, PROVIDED that the Purchase Price shall be reduced by
     the amount allocated to each Unsold Company and any associated Designated
     Receivables on Exhibit C and the conditions to Closing set forth in Section
     6 shall not be required to be fulfilled with respect to any Unsold Company
     by the Closing Date.

          (b)  If an Unsold Company is excluded from the sale and purchase of
     the Shares of the Companies on the Closing Date, then, from the Closing
     Date until the last day of the sixth calendar month following the Closing
     Date (the "FINAL SALE DATE"), the parties shall, in cooperation with each
     other, use their reasonable best efforts to obtain the consent relating
     thereto by such Final Sale Date. With

                                                            Amended and Restated
                                        2               Stock Purchase Agreement
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     respect to each consent that is obtained on or prior to the Final Sale
     Date, the parties shall, within ten days after such consent is obtained,
     consummate the sale and purchase of the Shares of the Unsold Company to
     which such consent relates and any associated Designated Receivables, at a
     purchase price equal to the amount allocated to such Unsold Company and any
     such Designated Receivables on Exhibit C, and otherwise on the terms and
     conditions contained in this Agreement, subject to appropriate
     modifications and adjustments as are necessary to reflect that the
     transactions contemplated by this Agreement will have been consummated at
     different times with respect to different Companies. References in this
     Agreement (other than in this Section 1.4 and Section 4.10) to the "Closing
     Date" and the Closing shall, with respect to the Unsold Company, be deemed
     to refer to the date or time, as the case may be, on which the sale of such
     Company is actually consummated.

          (c)  If any Unsold Company has not been sold to the Purchaser by the
     Final Sale Date, this Agreement shall, subject to Section 9.4, terminate
     with respect to such Unsold Company and any associated Designated
     Receivables.

          2.   REPRESENTATIONS AND WARRANTIES OF THE SELLERS. The Sellers,
jointly and severally, represent and warrant to the Purchaser that, except as
set forth in the schedules attached to this Agreement (collectively, the
"SCHEDULES," and each individually, a "SCHEDULE"):

          2.1  CORPORATE STATUS AND AUTHORITY OF THE SELLERS. Each Seller is a
company duly incorporated or organized, validly existing and in good standing
under the laws of its jurisdiction of organization and has all requisite
corporate power and authority to own its properties and assets and to carry on
its business as now being conducted. Each Seller has the requisite corporate
power and authority to execute and deliver this Agreement, the Local Purchase
Agreements to which it is or will be a party and, in the case of Spirent GmbH,
the German Asset Purchase Agreement (the Local Purchase Agreements and the
German Asset Purchase Agreement, the "ADDITIONAL TRANSFER AGREEMENTS"), and to
perform its obligations hereunder and thereunder. The execution and delivery of
this Agreement and the Additional Transfer Agreements by the Sellers party
hereto and thereto and the performance of the Sellers' respective obligations
hereunder and thereunder have been duly authorized by each such Seller's board
of directors, which constitutes all necessary corporate action on the part of
the Sellers party hereto and thereto or any Affiliate of such Sellers for such
authorization. This Agreement has been, and each of the Additional Transfer
Agreements when executed and delivered will be, duly executed and delivered by
the Sellers party hereto and thereto and constitutes or will constitute the
valid and binding obligation of the respective Sellers, enforceable against each
of them in accordance with the terms of such agreement, except as limited by
laws affecting the enforcement of creditor's rights generally or by general
equitable principles.

                                                            Amended and Restated
                                        3               Stock Purchase Agreement
<Page>

          2.2  NO CONFLICTS; CONSENTS AND APPROVALS, ETC.

          (a)  The execution and delivery of this Agreement and the Additional
     Transfer Agreements by the Sellers party hereto and thereto and the
     performance of their respective obligations hereunder and thereunder will
     not result in (i) any conflict with the Organizational Documents of any
     Seller or of any member of any Company Group, (ii) subject to obtaining the
     consents referred to in Section 2.2(b), any breach or violation of or
     default under any law, statute, regulation, judgment, order, decree,
     license, permit or other governmental authorization or any mortgage, lease,
     agreement, deed of trust, indenture or any other instrument to which any
     Seller or any member of any Company Group is a party or by which any of
     them or any of their respective properties or assets or any of the Shares
     are bound, or (iii) subject to obtaining the consents referred to in
     Section 2.2(b), the creation or imposition of any liens, security
     interests, adverse claims, charges or encumbrances ("LIENS") on any Shares,
     any asset of any member of any Company Group or any German Asset, except
     for such breaches, violations or defaults and such Liens which would not,
     individually or in the aggregate, reasonably be expected to have a material
     adverse effect on the financial condition, business, assets (including the
     German Assets) or operations of the Company Groups and the German Branches
     taken as a whole (a "MATERIAL ADVERSE EFFECT").

          (b)  No consent, approval or authorization of or filing with any third
     party or any governmental authority is required on the part of any Seller
     or any member of any Company Group in connection with the execution and
     delivery of this Agreement or the Additional Transfer Agreements or the
     consummation of the transactions contemplated hereby and thereby, except
     (i) as set forth on Schedule 2.2(b), (ii) filings required with respect to
     the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (the "HSR ACT")
     and (iii) filings, consents or approvals which, if not made or obtained,
     would not, individually or in the aggregate, reasonably be expected to have
     a Material Adverse Effect.

          2.3  CORPORATE STATUS OF THE COMPANIES. Each of the Companies is duly
incorporated or organized, validly existing and, to the extent applicable in the
jurisdiction in which each such Company is organized, in good standing under the
laws of its jurisdiction of organization. Each of the Companies has all
requisite corporate power and authority to conduct its business as now conducted
and to own or lease its properties now owned or leased. To the extent applicable
in the jurisdictions in which the Companies do business, each Company is duly
qualified to do business in each jurisdiction in which the failure to be so
qualified would, individually or in the aggregate, reasonably be expected to
have a Material Adverse Effect.

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                                        4               Stock Purchase Agreement
<Page>

          2.4  CAPITALIZATION. Schedule 2.4 lists, with respect to each Company,
(i) the jurisdiction of its incorporation or organization, (ii) the shares of
its capital stock that are authorized and that are issued and outstanding, and
(iii) the ownership of such issued and outstanding shares. The Shares have been
duly authorized and validly issued and, to the extent applicable in the
jurisdictions in which the Companies are organized, are fully paid and
non-assessable. Except as disclosed on Schedule 2.4, and except for the issuance
of additional Shares to the Sellers in connection with the settlement of
intercompany accounts, as described in Schedule 4.8, there are no outstanding
options, warrants, conversion or other rights or agreements of any kind (other
than this Agreement and Additional Transfer Agreements) relating to the
issuance, sale, purchase, redemption, repurchase, conversion, exchange,
registration, control, voting or transfer of any shares of capital stock of any
of the Companies, and no authorization therefor has been given. Each Seller owns
beneficially and of record the Shares indicated on Schedule 2.4 as owned by such
Seller, free and clear of any Liens, except as disclosed therein. Upon delivery
to the Purchaser pursuant to Section 1.2, the Shares will be duly authorized and
validly issued and, to the extent applicable in the jurisdictions in which the
Companies are organized, fully paid and non-assessable, free of any preemptive
or subscription rights and free and clear of any Liens other than Liens created
by or resulting from the actions of the Purchaser or any of its Affiliates.

          2.5  SUBSIDIARIES.

          (a)  Each of the Subsidiaries of the Companies is duly incorporated or
     organized, validly existing and, if a corporation, to the extent applicable
     in the jurisdiction in which each such Subsidiary is organized, in good
     standing under the laws of its jurisdiction of organization. Each of the
     Subsidiaries of the Companies has all requisite corporate, partnership or
     limited liability company power and authority to conduct its business as
     now conducted and to own or lease its properties now owned or leased. To
     the extent applicable in the jurisdictions in which such Subsidiaries do
     business, each Subsidiary is duly qualified to do business in each
     jurisdiction in which the failure to be so qualified would, individually or
     in the aggregate, reasonably be expected to have a Material Adverse Effect.

          (b)  Schedule 2.5 lists, with respect to each Subsidiary of the
     Companies, (i) the jurisdiction of its incorporation or organization, (ii)
     the shares of its capital stock or other equity interests that are
     authorized and that are issued and outstanding, and (iii) the ownership of
     such issued and outstanding shares or other equity interests. All shares of
     capital stock of such Subsidiaries have been duly authorized and validly
     issued and, to the extent applicable in the jurisdictions in which such
     Subsidiaries are organized, are fully paid and non-assessable. There are no
     outstanding options, warrants, conversion or other rights or agreements of
     any kind relating to the issuance, sale, purchase, redemption, repurchase,

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                                        5               Stock Purchase Agreement
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     conversion, exchange, registration, control, voting or transfer of any
     shares of capital stock or other equity interests of any of such
     Subsidiaries, and no authorization therefor has been given. Each Company
     and each Subsidiary thereof owns beneficially and of record the capital
     stock or other equity interests of its respective Subsidiaries indicated on
     Schedule 2.5 as owned by such Company or Subsidiary, free and clear of any
     Liens, except as disclosed therein. Except for the Subsidiaries of the
     Companies and of each such Subsidiary set forth on Schedule 2.5, none of
     the Companies or their Subsidiaries own, directly or indirectly, any
     capital stock or other equity securities of any corporation or has any
     direct or indirect equity or ownership interest in any partnership formed
     pursuant to a written partnership agreement, joint venture or other
     business.

          2.6  FINANCIAL STATEMENTS. Complete and correct copies of unaudited
balance sheets and related statements of income of the Company Groups and the
German Branches on a combined basis for the 1998, 1999 and 2000 fiscal years and
the six-month period ended June 30, 2001 are attached hereto as Exhibit D
(collectively, the "FINANCIAL STATEMENTS"). The Financial Statements were
prepared in accordance with United Kingdom generally accepted accounting
principles ("GAAP") applied (except as required to comply with changes to GAAP)
on a consistent basis throughout the periods presented, except that the
Financial Statements do not contain footnotes, and the Financial Statements
present fairly in all material respects the financial condition and results of
operations of the Company Groups and the German Branches on a combined basis as
of the dates or for the periods presented. The income statements included in the
Financial Statements reflect all of the business conducted by the Company Groups
during the periods presented.

          2.7  ABSENCE OF UNDISCLOSED LIABILITIES. Except for liabilities
reflected or reserved against in the Financial Statements or incurred in the
ordinary course of business since June 30, 2001, no member of any Company Group
or Spirent GmbH with respect to the German Branches has any liabilities, whether
known or unknown, absolute, accrued or contingent, other than (i) liabilities
that will be discharged prior to the Closing and (ii) other liabilities or
obligations which, individually or in the aggregate, would not reasonably be
expected to have a Material Adverse Effect.

          2.8  REAL PROPERTY; ASSETS.

          (a)  Schedule 2.8 lists all real property owned by any member of any
     Company Group or Spirent GmbH with respect to the German Branches (the
     "OWNED REAL PROPERTY") or leased by any member of any Company Group or
     Spirent GmbH with respect to the German Branches (the "LEASED REAL
     PROPERTY"). The Company Groups and Spirent GmbH with respect to the German
     Branches have good and marketable title to the Owned Real Property listed
     in Schedule 2.8 and good and valid leasehold interests in the Leased Real

                                                            Amended and Restated
                                        6               Stock Purchase Agreement
<Page>

     Property listed in Schedule 2.8 (other than the Taunton Lease, in which
     Spirent plc has a valid leasehold interest), in each case, free and clear
     of Liens, except for (i) Liens for taxes and other governmental charges and
     assessments which are not yet due and payable or which are being contested
     in good faith by appropriate proceedings and as to which reserves have been
     set aside in the Financial Statements to the extent required by GAAP, (ii)
     Liens of carriers, warehousemen, mechanics and materialmen and other like
     Liens arising in the ordinary course of business and as to which reserves
     have been set aside in the Financial Statements to the extent required by
     GAAP, (iii) easements, rights of way, title imperfections and restrictions,
     zoning ordinances and other similar encumbrances affecting the real
     property, (iv) statutory Liens in favor of lessors arising in connection
     with any property leased to any member of any Company Group or Spirent GmbH
     with respect to the German Branches, (v) Liens arising under the Contracts
     disclosed pursuant to Section 2.9, (vi) Liens created by this Agreement and
     the Additional Transfer Agreements, PROVIDED that in each case referred to
     in (i) through (vi) above, such Liens and encumbrances do not impair or
     prevent the use of the Owned Real Property or Leased Real Property as
     presently used, and (vii) any other Liens which do not materially interfere
     with the current use of the properties affected thereby ("PERMITTED
     LIENS").

          (b)  Each lease (including any option to purchase contained therein)
     pursuant to which any member of any Company Group or Spirent GmbH with
     respect to the German Branches leases any Leased Real Property (the
     "LEASES") is in full force and effect and, to the knowledge of the
     Sellers, is enforceable against the landlord which is party thereto in
     accordance with its terms. There exists no material default or event of
     default (or any event that with notice or lapse of time or both would
     become a material default) on the part of any member of any Company Group
     or Spirent GmbH with respect to the German Branches under any Lease. The
     Sellers have made available to the Purchaser complete and correct copies of
     all Leases including all amendments thereto. No member of any Company Group
     or Spirent GmbH with respect to the German Branches has received any
     written notice of any default under any Lease by which it leases any Leased
     Real Property nor any other termination notice with respect thereto.

          (c)  The Company Groups have legal and beneficial ownership of all
     tangible personal property and assets (other than the German Assets)
     reflected in the unaudited combined balance sheet as of June 30, 2001
     included in the Financial Statements, except for properties and assets
     disposed of in the ordinary course of business since the date of such
     balance sheet, in each case free and clear of Liens other than Permitted
     Liens. The Company Groups own or have the right to use all of the
     properties and assets necessary for the conduct of their Business. Each
     such tangible asset is in such condition and repair (subject to normal wear
     and tear) as is suitable for its current use, except for such exceptions as
     would not,

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                                        7               Stock Purchase Agreement
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     individually or in the aggregate, reasonably be expected to have a Material
     Adverse Effect.

          (d)  Spirent GmbH has legal and beneficial ownership of all of the
     tangible personal property and assets to be transferred pursuant to the
     German Asset Purchase Agreement (the "GERMAN ASSETS"), in each case free
     and clear of Liens other than Permitted Liens. Each German Asset is in such
     condition and repair (subject to normal wear and tear) as is suitable for
     its current use, except for such exceptions as would not, individually or
     in the aggregate, reasonably be expected to have a Material Adverse Effect.

          2.9  CONTRACTS. Schedule 2.9 lists all agreements, contracts and
commitments of the following types to which any member of any Company Group is a
party or in which any German Branch is named as a party or which relate
exclusively to the operations of any German Branch or by which any member of any
Company Group or any German Branch or any of their properties are bound as of
the date hereof and will be bound following the Closing (other than real
property leases and labor or employment-related agreements, which are provided
for in Sections 2.8 and 2.10, respectively):

          (a)  joint venture, partnership, management and development
     agreements;

          (b)  mortgages, indentures, loan or credit agreements, guarantee
     agreements, pledge, security agreements and other agreements and
     instruments relating to the borrowing of money or extension of credit in
     any case in excess of US$250,000;

          (c)  (i) orders and other contracts or arrangements for the purchase
     or sale of materials, supplies, products or services (excluding contracts
     that are only in the form of customary purchase orders and other orders or
     contracts entered into in the ordinary course of business), (ii) contracts
     for the lease of personal property to or from any Person, and (iii)
     contracts or arrangements with distributors of or for the marketing of the
     products of the Company Groups or German Branches (excluding contracts with
     distributors that are only in the form of customary purchase orders) which,
     in each case, (x) are not cancelable by any member of any Company Group or
     Spirent GmbH with respect to the German Branches on notice of 60 days or
     less and (y) involve annual payments of at least US$50,000 or aggregate
     payments of at least US$250,000;

          (d)  contracts prohibiting or restricting the ability of any member of
     a Company Group or the German Branches to engage in any business or operate
     in any geographical area or to compete with any Person;

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                                        8               Stock Purchase Agreement
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          (e)  acquisition or divestiture agreements relating to the acquisition
     or sale of any business, or of any capital stock of or other equity
     interest in any Person, by any member of a Company Group or Spirent GmbH
     with respect to the German Branches and containing continuing indemnity
     obligations of such member of a Company Group or Spirent GmbH with respect
     to the German Branches;

          (f)  contracts providing for future payments that are conditioned, in
     whole or in part, on a change in control of any member of the Company
     Groups;

          (g)  other agreements, contracts, arrangements and commitments which,
     in each case, (i) are not cancelable by any member of any Company Group on
     notice of 60 days or less and (ii) require payment by such Company Group
     member after the date hereof of more than US$250,000;

          (h)  contracts that are otherwise material to the Business of the
     Company Groups and the German Branches as a whole; and

          (i)  purchase orders of customers to whom aggregate sales by the
     Company Groups or the German Branches for the twelve-month period ending
     June 30, 2001 were in excess of US$1,000,000.

     The Sellers have made available to the Purchaser copies of all of the
contracts listed in Schedule 2.9. Each such contract is a valid and binding
agreement of the relevant member of a Company Group or Spirent GmbH with respect
to the German Branches, is in full force and effect and, to the knowledge of the
Sellers, is enforceable against the parties thereto. No member of any Company
Group or Spirent GmbH with respect to the German Branches nor, to the knowledge
of the Sellers, any other Person is in default under any of the contracts listed
in Schedule 2.9, except for such defaults which would not, individually or in
the aggregate, reasonably be expected to have a Material Adverse Effect.

          2.10 EMPLOYMENT AGREEMENTS AND EMPLOYEE PLANS ETC.

          (a)  EMPLOYMENT AGREEMENTS. Schedule 2.10(a) lists all written
     agreements, contracts and commitments of the following types to which any
     member of any Company Group or Spirent GmbH with respect to the German
     Branches is a party or which relate to the current employment of any
     Company Employee: (i) employment and consulting agreements (including
     severance and retention agreements) and (ii) collective bargaining
     agreements.

          (b)  EMPLOYMENT PLANS. Schedule 2.10(b) lists all "employee benefit
     plans" as defined in section 3(3) of the Employee Retirement Income
     Security Act of 1974 ("ERISA") (whether or not such plans are subject to
     ERISA), maintained

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     by or covering employees of any member of any Company Group and any other
     plans, programs, policies or other arrangements (other than those listed in
     Schedule 2.10(a)) including profit sharing, pension, retirement, bonus,
     incentive compensation, stock option, deferred compensation or other
     written material employee benefit plans, agreements, contracts or
     commitments for the benefit of the employees of any member of any Company
     Group, including such plans of the Sellers or any Affiliate of the Sellers
     covering employees of any member of any Company Group or plans in which
     employees of any member of any Company Group participate (collectively, the
     "PLANS").

          (c)  GENERAL COMPLIANCE. The Companies have made all contributions
     required to have been made under the terms of any Plan or pursuant to any
     applicable collective bargaining agreement or applicable law within the
     time prescribed by any such Plan, agreement or law and each Plan has been
     operated and administered in accordance with its terms and applicable law,
     except for any failures to make plan contributions, to so operate or
     administer that, individually or in the aggregate, have not had or resulted
     in a Material Adverse Effect.

          (d)  U.S. COMPANIES.

               (i)  ERISA. All Plans that are subject to ERISA comply in all
          respects with the requirements of ERISA and the Internal Revenue Code
          of 1986, as amended (the "CODE"), except for any failures to comply
          which would not, individually or in the aggregate, reasonably be
          expected to have a Material Adverse Effect. No Plan (other than a
          multiemployer plan as defined in section 3(37) of ERISA) to which
          either the Seller or any member of the same controlled group of
          corporations as the Seller, within the meaning of section 4001(a)(3)
          of ERISA, contributes and which is subject to Part 3 of Subtitle B of
          Title I of ERISA has incurred any "accumulated funding deficiency"
          within the meaning of section 302 of ERISA or section 412 of the Code
          and no material liability (other than for annual premiums) to the
          Pension Benefit Guaranty Corporation has been incurred by any member
          of any Company Group with respect to any such Plan. No member of any
          Company Group has incurred any material liability for any tax or
          penalty imposed by section 4975 of the Code or section 502(i) of
          ERISA. No member of any Company Group has made a complete or partial
          withdrawal from any multiemployer plan as defined in section 3(37) of
          ERISA so as to incur any partial or full withdrawal liability under
          section 4201 of ERISA (without regard to subsequent reduction or
          waiver of such liability under section 4207 or 4208 of the Code).
          There are no material pending or, to the Sellers' knowledge,
          threatened claims by or on behalf of any of the Plans or by any
          employee involving any such Plan (other than routine claims for
          benefits).

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                                       10               Stock Purchase Agreement
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               (ii) TAX QUALIFICATION. Each Plan intended to be qualified under
          section 401(a) of the Code, and the trust (if any) forming a part
          thereof, has received a favorable determination letter from the IRS as
          to its qualification under the Code and to the effect that each such
          trust is exempt from taxation under section 501(a) of the Code, and,
          nothing has occurred since the date of such determination letter that
          will adversely affect such qualification or tax-exempt status.

          (e)  There are no pending or, to the knowledge of the Sellers,
     threatened labor grievances or unfair labor practice claims or charges
     against any member of any Company Group or with respect to the German
     Branches which, individually or in the aggregate, would have a Material
     Adverse Effect. As of the date hereof, (i) to the knowledge of the Sellers,
     there are no organizing efforts by any union or other group seeking to
     represent any employees of any member of the Company Groups or the German
     Branches except as set forth on Schedule 2.10 and (ii) there are no strikes
     or other material labor disputes against any member of the Company Groups
     or the German Branches pending or, to the knowledge of the Sellers,
     threatened.

          2.11 INTELLECTUAL PROPERTY. Schedule 2.11 lists all material
trademarks, trade names, service marks, copyrights, patents and similar rights
that are registered or subject to an application for registration (collectively,
"INTELLECTUAL PROPERTY") owned in whole or in part by any member of a Company
Group and used by such member of a Company Group in its Business or owned in
whole or in part by Spirent GmbH and used in the Business of any German Branch
("OWNED INTELLECTUAL PROPERTY"). Except for Permitted Liens, the Company Groups
and Spirent GmbH with respect to the German Branches own the Owned Intellectual
Property free and clear of all Liens. The Company Groups have taken commercially
reasonable steps in accordance with normal industry practice to protect and
maintain in force the Owned Intellectual Property and trade secrets used in the
operation of their business. No member of any Company Group or Spirent GmbH with
respect to the German Branches has received any written notice or claim that it
is infringing on the Intellectual Property or trade secret rights of any Person
and the Sellers have no knowledge of any infringement by any Person of the Owned
Intellectual Property or trade secret rights owned by any member of a Company
Group or Spirent GmbH with respect to the German Branches. Schedule 2.11 sets
forth a complete and correct list, as of the date hereof, of all material
written licenses to Intellectual Property or trade secret rights (other than
licenses for "off-the-shelf" software) to which any member of any Company Group
or Spirent GmbH with respect to the German Branches is a party, pursuant to
which (x) such member of a Company Group or Spirent GmbH with respect to the
German Branches permits any Person or entity to use any of the Owned
Intellectual Property or trade secret rights owned by such member of a Company
Group or Spirent GmbH with respect to the German Branches, or (y) any Person or
entity permits such member of a Company Group or Spirent GmbH with respect to
the German

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                                       11               Stock Purchase Agreement
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Branches to use any trademarks, trade names, service marks, copyrights, trade
secret rights or patents not owned by such member of a Company Group or Spirent
GmbH with respect to the German Branches (collectively, the "LICENSES"). The
Seller has made available to the Purchaser complete and correct copies of the
Licenses. No member of any Company Group or Spirent GmbH with respect to the
German Branches, nor, to the Sellers' knowledge, any other party to a License,
is in default under such License, and each License is in full force and effect
as to each member of any Company Group party thereto or as to Spirent GmbH to
the extent Spirent GmbH is party to any such License with respect to the German
Branches, as the case may be, and to the Sellers' knowledge, as to each other
party thereto, except for such defaults and failures to be so in full force and
effect as, individually or in the aggregate, would not reasonably be expected to
have a Material Adverse Effect. The Owned Intellectual Property identified in
Schedule 2.11, together with the rights granted to the members of the Company
Groups and Spirent GmbH with respect to the German Branches under the Licenses
identified in Schedule 2.11 and any licenses for off-the-shelf software not on
Schedule 2.11, constitutes all the material Intellectual Property used by the
members of the Company Groups and the German Branches in the operation of their
business as it is currently conducted and no other material Intellectual
Property rights or Licenses are necessary to operate such business after the
Closing Date in substantially the same manner as such business has been operated
by the members of the Company Groups and the German Branches prior thereto.

          2.12 GOVERNMENTAL AUTHORIZATIONS; COMPLIANCE WITH LAW. The Company
Groups and Spirent GmbH with respect to the German Branches, as required, hold
all licenses, permits and other governmental authorizations material to their
respective Businesses, and each member of the Company Groups and Spirent GmbH
with respect to the German Branches is in compliance with all laws, statutes,
rules, regulations, judgments, orders, decrees, permits, concessions, franchises
or other governmental or regulatory authorizations or approvals, whether U.S.
federal, state or local or non-U.S., applicable to it or to any of its
properties, except for such failures to comply which would not, individually or
in the aggregate, reasonably be expected to have a Material Adverse Effect. This
Section 2.12 does not relate to employee benefits matters, which are the subject
of Section 2.10, tax matters, which are the subject of Section 2.14, or
environmental matters, which are the subject of Section 2.16.

          2.13 LITIGATION. There are no judicial or administrative actions,
proceedings or investigations pending or, to the knowledge of the Sellers,
threatened against any Seller or against any member of any Company Group or
Spirent GmbH with respect to the German Branches and there are no judgments or
outstanding orders, injunctions, decrees, stipulations or awards rendered by a
governmental, judicial or administrative authority against any member of the
Company Groups, the German Branches or any of their properties or Business which
(i) if determined adversely, individually or in the aggregate, would reasonably
be expected to have a Material

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                                       12               Stock Purchase Agreement
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Adverse Effect, or (ii) question the validity of this Agreement or the
Additional Transfer Agreements or any action taken or to be taken by any Seller
or by any member of any Company Group in connection herewith or therewith.

          2.14 TAXES. Except as disclosed on Schedule 2.14, (i) each member of
the Company Groups (including for this specific purpose Spirent GmbH, but only
with respect to the German Branches), and any affiliated group, within the
meaning of Section 1504 of the Code, of which any member of the Company Groups
is a member, has filed or caused to be filed, in a timely manner (within any
applicable extension periods) all material Tax Returns relevant to the members
of the Company Groups required to be filed by the Code or by applicable state,
local or foreign laws in respect of Taxes, (ii) all such Tax Returns are correct
and complete in all material respects, (iii) all Taxes due and payable with
respect to the periods covered by such Tax Returns have been paid in full when
due and payable and the Financial Statements reflect adequate reserves in
accordance with GAAP for all Taxes not yet due and payable, (iv) with respect to
U.S. Companies and their U.S. Subsidiaries no member of the Company Groups is a
party to any agreement, contract, arrangement or plan that would be likely to
result, separately or in the aggregate, in connection with this Agreement or any
change of control of any member of the Company Groups, in the payment of any
"excess parachute payments" within the meaning of Section 280G of the Code, (v)
no member of the Company Groups is a party to any tax sharing agreements or
similar agreement, (vi) all employment and withholding Taxes required to be paid
or withheld by or on behalf of any member of any Company Group have been paid or
properly set aside in accounts for such purpose, (vii) no written agreement or
other document extending, or having the effect of extending, the period of
assessment or collection of any Taxes payable by any member of any Company Group
is currently in effect, (viii) no member of any Company Group is, as of the date
hereof, the beneficiary of any extension of time (other than an automatic
extension of time not requiring the consent of the Internal Revenue Service or
any other taxing authority) within which to file any Tax Return not previously
filed, (ix) no amount will be required to be deducted or withheld pursuant to
section 1445(a) of the Code in connection with the transactions contemplated by
this Agreement and (x) as of the date hereof, there are not pending any audits,
examinations, investigations or other proceedings in respect of Taxes payable by
any member of any Company Group. "TAXES" means all U. S. or non-U.S. federal,
national, state or local taxes, assessments, levies or other governmental
charges in the nature of taxes, including all income, franchise, withholding,
unemployment insurance, social security, PAYE, sales, use, excise, real and
personal property, stamp, transfer, VAT and workers' compensation taxes,
together with all interest, penalties and additions payable with respect
thereto. "TAX RETURN" means all returns and reports required to be supplied to a
taxing authority relating to Taxes.

          2.15 ABSENCE OF CHANGES. Since June 30, 2001, other than in connection
with the transactions contemplated by this Agreement and the Additional Transfer

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                                       13               Stock Purchase Agreement
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Agreements (including without limitation the elimination of intercompany
accounts pursuant to Section 4.8), (x) the Company Groups have conducted their
business, and Spirent GmbH has conducted the business of the German Branches, in
the ordinary course, in substantially the same manner in which it has been
previously conducted, (y) no events or circumstances have occurred that,
individually or in the aggregate, would reasonably be expected to have a
Material Adverse Effect (other than events or circumstances that generally
affect companies that do business in the industry or jurisdictions in which the
members of the Company Groups do business), and (z) neither any member of any
Company Group nor, where applicable in clauses (b), (d) and (e) to the German
Branches, Spirent GmbH has:

          (a)  purchased, acquired, issued, sold or redeemed any of its shares
     of capital stock or ownership interests;

          (b)  mortgaged, pledged or subjected to any Lien any of its properties
     or assets (including the German Assets), except for Liens incurred in the
     ordinary course of business and Permitted Liens;

          (c)  except as required by GAAP, made any material change in its
     accounting principles or the methods by which such principles are applied
     for financial reporting purposes;

          (d)  increased the compensation of any officer or Company Employee
     other than (i) in the ordinary course of business or (ii) to comply with
     applicable law;

          (e)  disposed or agreed to dispose of any material properties or
     assets, including the German Assets, used in the conduct of their business,
     other than in the ordinary course of business; or

          (f)  canceled or forgiven any debts or claims except in the ordinary
     course of business;

PROVIDED, HOWEVER, that no provision of this Agreement shall restrict the
ability of any member of any Company Group or Spirent GmbH to distribute all or
any portion of its cash, cash equivalents and intercompany accounts receivable
or use all or any portion of its cash and cash equivalents, through legal
dividends to its stockholders, repayment of outstanding liabilities or
otherwise.

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                                       14               Stock Purchase Agreement
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          2.16 ENVIRONMENTAL MATTERS. Except as would not reasonably be expected
to have a Material Adverse Effect:

          (a)  the Company Groups, the German Branches, the Owned Real Property
     and the Leased Real Property are in compliance with all applicable
     Environmental Laws;

          (b)  the Company Groups and the German Branches have obtained, and are
     in compliance with, all permits and authorizations required under
     applicable Environmental Laws;

          (c)  no member of any Company Group or Spirent GmbH with respect to
     the German Branches has received from any governmental authority or Person
     any notice of violation, alleged violation, non-compliance, liability or
     potential liability regarding compliance with or liability under applicable
     Environmental Laws and, to the knowledge of the Sellers, there are no facts
     or circumstances that would reasonably be expected to form the basis of any
     liability or claim against the Company Groups or Spirent GmbH with respect
     to the German Branches regarding compliance with or liability under
     Environmental Laws;

          (d)  no judicial proceeding or governmental or administrative action
     is pending or, to the knowledge of the Sellers, threatened, under any
     applicable Environmental Law pursuant to which any member of any Company
     Group or Spirent GmbH with respect to the German Branches is or, to the
     knowledge of the Sellers, will be named as a party;

          (e)  no member of any Company Group or Spirent GmbH with respect to
     the German Branches has entered into any agreement with any governmental
     authority or Person pursuant to which such member of a Company Group or
     Spirent GmbH with respect to the German Branches has assumed responsibility
     for the remediation of any condition resulting from the release, treatment,
     storage or disposal of Hazardous Substances;

          (f)  to the knowledge of the Sellers, all material environmental site
     assessments, compliance audits and remediation studies relating to
     environmental conditions at the Owned Real Property and the Leased Real
     Property prepared by or for any Seller, or by or for any member of any
     Company Group or any German Branch since such member of a Company Group or
     such German Branch has been owned or controlled (directly or indirectly) by
     a Seller, have been made available to the Purchaser; and

          (g)  nothing set forth in the Schedules would reasonably be expected
     to form the basis for a liability or claim against the Company Groups or
     Spirent

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                                       15               Stock Purchase Agreement
<Page>

     GmbH with respect to the German Branches regarding compliance with or
     liability under Environmental Laws that would have a Material Adverse
     Effect.

     Notwithstanding any of the representations and warranties contained
elsewhere in this Agreement, environmental matters shall be governed exclusively
by this Section 2.16.

          2.17 BANKING AND AGENCY ARRANGEMENTS. Schedule 2.17 sets forth a list
of:

          (a)  each bank or similar financial institution in which any member of
     any Company Group or any German Branch has an account or safe deposit box
     or other custodial arrangement and the numbers of such accounts or safe
     deposit boxes maintained by such member of a Company Group or such German
     Branch; and

          (b)  the names of all persons authorized to draw on each such account
     or to have access to any such safe deposit box facility or custodial
     arrangement.

          2.18 AFFILIATE TRANSACTIONS. Except as listed on the Schedules, no
member of any Company Group or Spirent GmbH with respect to the German Branches
is a party to any written or enforceable oral agreement with (a) any of its
directors or officers or (b) any Seller or any Affiliate of any Seller other
than any of the members of the Company Groups or Spirent GmbH with respect to
the German Branches (such Affiliates, "NON-COMPANY AFFILIATES"). Schedule 2.18
sets forth a list of all material services provided by any Seller or Non-Company
Affiliate to any member of any Company Group or any German Branch, whether
pursuant to a written agreement or otherwise.

          2.19 BROKERS. All negotiations relating to this Agreement and the
Additional Transfer Agreements and the transactions contemplated hereby and
thereby have been carried out without the intervention of any Person acting on
behalf of any Seller or any Company in such manner as to give rise to any valid
claim against the Purchaser or any member of any Company Group for any brokerage
or finder's commission, fee or similar compensation, except for Morgan Stanley &
Co. Limited, whose fees and expenses in respect hereof and thereof will be the
responsibility of the Sellers or one or more Non-Company Affiliates.

          3. REPRESENTATIONS AND WARRANTIES OF THE PURCHASER. The Purchaser
represents to the Sellers as follows:

          3.1  CORPORATE STATUS AND AUTHORITY. The Purchaser is a corporation
duly organized, validly existing and in good standing under the laws of its
jurisdiction of organization or has the power to carry on its business as now
being conducted. The

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                                       16               Stock Purchase Agreement
<Page>

Purchaser has the requisite corporate power and authority to execute and deliver
this Agreement and the Additional Transfer Agreements and perform its
obligations hereunder and thereunder. The execution, delivery and performance of
this Agreement and the Additional Transfer Agreements have been duly authorized
by the board of directors of the Purchaser, which constitutes all necessary
corporate action on the part of such entity for such authorization. This
Agreement has been, and each of the Additional Transfer Agreements when executed
and delivered will be, duly executed and delivered by the Purchaser and
constitutes or will constitute the valid and binding obligation of the
Purchaser, enforceable against it in accordance with the terms of such
agreement, except as limited by laws affecting the enforcement of creditors'
rights generally or by general equitable principles.

          3.2  NO CONFLICTS; CONSENTS AND APPROVALS, ETC.

          (a)  The execution and delivery of this Agreement and the Additional
     Transfer Agreements by the Purchaser and the performance of its obligations
     hereunder and thereunder will not result in (i) any conflict with the
     Organizational Documents of the Purchaser, (ii) any breach or violation
     of or default under any law, statute, regulation, judgment, order, decree,
     license, permit or other governmental authorization or any mortgage,
     lease, agreement, deed of trust, indenture or any other instrument to which
     the Purchaser is a party or by which the Purchaser or any of its properties
     or assets are bound, or (iii) the creation or imposition of any Lien on any
     assets of the Purchaser, except for such breaches, violations or defaults
     and such Liens which would not, individually or in the aggregate, impair
     the ability of the Purchaser to fulfill its obligations hereunder.

          (b)  No consent, approval or authorization of or filing with any third
     party or governmental authority is required on the part of the Purchaser in
     connection with the execution and delivery of this Agreement or the
     Additional Transfer Agreements or the consummation of the transactions
     contemplated hereby and thereby, except (i) as set forth on Schedule
     3.2(b), (ii) filings required with respect to the HSR Act and (iii) for
     such other consents, approvals, authorizations, and filings the failure to
     obtain which would not adversely affect the ability of the Purchaser to
     consummate its obligations hereunder.

          3.3  FINANCIAL ABILITY TO PERFORM. The Purchaser has available cash
funds sufficient to consummate the transactions contemplated by this Agreement
and the Additional Transfer Agreements.

          3.4  LITIGATION. There are no judicial or administrative actions,
proceedings or investigations involving the Purchaser that are pending or, to
the knowledge of the Purchaser, threatened, which question the validity of this
Agreement or

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                                       17               Stock Purchase Agreement
<Page>

the Additional Transfer Agreements or any action taken or to be taken by it in
connection herewith or therewith.

          3.5  PURCHASE FOR INVESTMENT. The Purchaser is acquiring the Shares
and Designated Receivables for investment and not with a view toward any resale
or distribution thereof except in compliance with the Securities Act of 1933, as
amended.

          3.6  BROKERS. All negotiations relating to this Agreement and the
Additional Transfer Agreements and the transactions contemplated hereby and
thereby have been carried out without the intervention of any Person acting on
behalf of the Purchaser in such manner as to give rise to any valid claim
against the Seller or any of its Affiliates for any brokerage or finder's
commission, fee or similar compensation.

          4.   COVENANTS.

          4.1  SATISFACTION OF CLOSING CONDITIONS. The parties shall use their
commercially reasonable best efforts to bring about the satisfaction as soon as
practicable of all the conditions to Closing contained in Section 6. Without
limiting the generality of the foregoing, the parties shall apply for and
diligently prosecute all applications for, and shall use their commercially
reasonable best efforts promptly to obtain, such consents, waivers, releases,
authorizations and approvals from such third parties and governmental
authorities as shall be necessary to permit the consummation of the transactions
contemplated by this Agreement and the Additional Transfer Agreements or to
avoid a Material Adverse Effect including, without limitation, (i) making the
requisite filings with the Federal Trade Commission and the Antitrust Division
of the Department of Justice pursuant to the HSR Act, as well as any filings
with, or submissions to, any governmental, regulatory or administrative
authority in any jurisdiction where such filing or submission is required in
connection with the transactions contemplated by this Agreement and the
Additional Transfer Agreements, and (ii) in the case of the Purchaser, using
commercially reasonable best efforts to deliver replacement guaranties, bonds or
other undertakings, as the case may be, and/or other consideration to the
beneficiaries of the Guaranties and Bonds listed on Schedule 4.1 and any other
Guaranties or Bonds issued or obtained in the ordinary course of business prior
to the Closing Date on substantially similar terms as such Guaranties and Bonds,
and obtaining the complete and unconditional release of the Sellers and any
Non-Company Affiliates from all obligations in connection with all of such
Guaranties and Bonds.

          4.2  CONDUCT OF BUSINESS, ETC.

          (a)  From the date hereof until the Closing, except for (i) entering
     into and performing under this Agreement and the Additional Transfer
     Agreements, (ii) the matters referred to in Schedule 4.2, (iii) the effect
     of the consummation of the transactions contemplated by this Agreement and
     the Additional Transfer

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                                       18               Stock Purchase Agreement
<Page>

     Agreements and (iv) as otherwise consented to by the Purchaser in writing,
     such consent not to be unreasonably withheld, the Sellers shall cause the
     Company Groups and the German Branches to conduct their Business in the
     ordinary course in substantially the same manner in which it previously has
     been conducted and not take any action that would cause a breach of Section
     2.15.

          (b)  Notwithstanding Section 4.2(a), except as contemplated by this
     Agreement and the Additional Transfer Agreements, the Sellers shall cause
     each member of the Company Groups not to, and Spirent GmbH shall not with
     respect to the German Branches, without the prior written approval of the
     Purchaser, which shall not be unreasonably withheld:

               (i)   amend its Organizational Documents;

               (ii)  incur any third party indebtedness for borrowed money,
          except for (x) borrowings in the ordinary course of business
          consistent with past practice and (y) indebtedness that will be
          discharged prior to or on the Closing Date or refinanced by loans that
          give rise to Designated Receivables;

               (iii) make any acquisition or disposition of capital stock or
          other securities or assets of any Person outside of the ordinary
          course of business and in excess of $250,000, excluding all
          acquisitions of inventory and equipment in the ordinary course of
          business consistent with past practice;

               (iv)  adopt, amend in any material respect, enter into or
          terminate any Plan, severance plan, collective bargaining agreement,
          employment contract or make awards or distributions under any Plan,
          except awards or distributions to any participant or employee in the
          ordinary course consistent with past practice;

               (v)   make any election inconsistent with past practice relating
          to Taxes unless such election is required by law or would not
          reasonably be expected to have a Material Adverse Effect; or

               (vi)  agree, commit or resolve to do or authorize any of the
          foregoing.

          4.3  ACCESS AND INFORMATION.

          From the date hereof until the Closing, the Sellers shall cause the
     Company Groups to give the Purchaser and its representatives reasonable
     access at all reasonable times to the properties, books and records of the
     Company

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                                       19               Stock Purchase Agreement
<Page>

     Groups and to furnish such information and documents in their possession
     relating to the Company Groups as the Purchaser may reasonably request, and
     Spirent GmbH shall give the Purchaser and its representatives reasonable
     access at all reasonable times to the properties, books and records of the
     German Branches and shall furnish such information and documents in its
     possession relating to the German Branches as the Purchaser may reasonably
     request, PROVIDED that in each case the Purchaser shall not be entitled to
     any such access, information or documents for the purposes of conducting
     any environmental audit or assessment without the prior written consent of
     the Spirent plc. All such information and documents obtained by the
     Purchaser shall be subject to the terms of the Confidentiality Agreement,
     dated June 19, 2001 (the "CONFIDENTIALITY AGREEMENT"), between the
     Purchaser and Spirent plc with respect to the transactions contemplated by
     this Agreement and the Additional Transfer Agreements. The Purchaser hereby
     agrees that the provisions of the Confidentiality Agreement will apply to
     any properties, books, records, data, documents and other information
     relating to the Sellers or any Non-Company Affiliate provided to the
     Purchaser or its Affiliates or any of their respective advisers or
     employees pursuant to this Agreement whether before or after the Closing.

          4.4  TAXES.

          (a)  INDEMNITY. Except as otherwise provided in Section 4.4(h), the
     Sellers shall pay (without duplication of amounts otherwise payable), and
     shall indemnify and hold harmless the Purchaser from and against, (i) all
     liability for Taxes of, or with respect to, any member of the Company
     Groups or any German Branch (other than any liability described in Section
     4.4(a)(ii)) and (ii) all liability of any member of the Company Groups for
     Taxes (as a result of Treasury Regulationss.1.1502-6(a) or otherwise) of
     the Sellers or any other corporation which is or has been affiliated with
     any member of the Company Groups prior to the Closing, in each case for
     taxable periods (or portions thereof in the case of a Straddle Period)
     ending on or before the Closing Date to the extent such Taxes exceed the
     reserves for Taxes reflected in the June 30, 2001 balance sheet in the
     Financial Statements (other than reserves for deferred Taxes or U.S.
     Combined Income Taxes) including, without limitation, reasonable
     out-of-pocket attorneys' fees and other costs attributable to the
     assessment and collection thereof, other than any such Taxes directly
     attributable to any act or omission by the Purchaser (including, without
     limitation, making an election pursuant to Sections 338 or 336(e) of the
     Code or any similar provision of U.S. state or local or non-U.S. law) or,
     after the Closing, any member of the Company Groups (other than any such
     action or omission expressly required by applicable law or expressly
     required or expressly permitted by this Agreement). Notwithstanding the
     foregoing sentence, the amount that the Sellers shall be required to pay to
     the Purchaser for Taxes of or

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                                       20               Stock Purchase Agreement
<Page>

     payable by any Company listed on Exhibit B-1 hereto or any of such
     Company's Subsidiaries or Thermometrics Beijing shall be the product of the
     amount otherwise required to be paid pursuant to the first sentence of this
     Section 4.4(a) and the Applicable Percentage. The Purchaser shall, or shall
     cause the applicable member of the Company Groups or any German Branch to,
     pay and indemnify and hold harmless the Sellers from and against (x) all
     Taxes of, with respect to or payable by such member or such German Branch
     which are not described as being the responsibility of the Sellers in the
     first two sentences of this Section 4.4(a), (y) any Taxes (other than U.S.
     Combined Income Taxes) resulting from the failure of such member or such
     German Branch to pay, after the Closing Date, Taxes reflected in the June
     30, 2001 balance sheet in the Financial Statements and (z) any Taxes
     resulting from an election made by Purchaser under Sections 338 or 336(e)
     of the Code or any similar provision of U.S. state or non-U.S. local law
     (including in the case of each of the foregoing clauses, and without
     limitation, reasonable out-of-pocket attorneys' fees and other costs
     attributable to the assessment and collection thereof).

          (b)  STRADDLE PERIOD. The Purchaser and the Sellers shall, to the
     extent permitted by applicable law, elect with the relevant taxing
     authority to close the taxable period of each member of any Company Group
     on the Closing Date. Where a taxable period begins before the Closing Date
     and ends after the Closing Date (a "STRADDLE PERIOD"), the portion of any
     Taxes in such Straddle Period that are allocable to the portion of the
     period ending on the Closing Date shall be determined using the interim
     closing of the books method as of the Closing Date, except that (A)
     exemptions, allowances or deductions that are calculated on an annual basis
     shall be apportioned on a per diem basis, and (B) real and personal
     property taxes shall likewise be apportioned on a per diem basis.

          (c)  RETURNS. The Sellers shall prepare or cause to be prepared and
     shall timely file or cause to be timely filed all Tax Returns in
     respect of each member of any Company Group and each German Branch (i) that
     are required to be filed on or prior - to the Closing Date or (ii) that
     relate to any taxable period ending on or before the Closing Date and that
     are not required to be filed on or prior to the Closing Date except, in
     the case of this clause (ii), Tax Returns in respect of VAT or the United
     Kingdom PAYE Tax. The Purchaser shall cooperate with the Sellers to enable
     the Sellers to file any such Tax Returns after the Closing Date including,
     without limitation, by making available to the Sellers knowledgeable
     personnel of the Companies or their respective Subsidiaries and by
     consenting to the Sellers' use of external advisors of the Companies or
     their respective Subsidiaries in connection with preparing such Tax
     Returns. The Purchaser shall prepare or cause to be prepared and file or
     cause to be filed all other Tax Returns in respect of each member of any
     Company Group and each German Branch that are not required to be prepared
     by the Sellers pursuant to the first sentence of this

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                                       21               Stock Purchase Agreement
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     Section 4.4(c). Any Tax Return covering a Straddle Period (a "STRADDLE
     RETURN") shall, insofar as it relates to any member of any Company Group or
     any German Branch, be prepared by the Purchaser on a basis consistent with
     the last previous such return filed, except as required by changes in law.
     Straddle Returns shall be subject to the pre-filing review procedure
     described in Section 4.4(e). The Purchaser shall not, and shall not permit
     any member of any Company Group to, file any amended Tax Return in respect
     of any member of any Company Group or any German Branch that relates to any
     taxable period ending on or prior to the Closing Date or file any amended
     Straddle Return without the consent of the applicable Seller which consent,
     in the case of a Straddle Return, shall not be unreasonably withheld.

          (d)  REFUNDS. The Sellers shall be entitled to retain, or receive
     immediate payment from any member of any Company Group or the Purchaser of,
     an amount equal to any refund for Taxes that were paid with respect to a
     period or portion thereof ending on or prior to the Closing Date
     (including, without limitation, refunds arising by reason of amended
     returns filed after the Closing Date) plus any interest thereon received
     with respect thereto from the applicable taxing authority relating to any
     member of any Company Group or any German Branch. In addition, if as a
     result of an adjustment on audit by a taxing authority or as a result of an
     administrative or judicial proceeding for periods or portions thereof
     ending on or prior to the Closing Date of any member of any Company Group
     or any German Branch, expenses which had been deducted are required to be
     capitalized, or deductions or credits that had been deducted or claimed on
     a Tax Return are required to be deferred to any period or partial period
     ending after the Closing Date, and in connection with such audit or
     administrative or judicial proceeding an amount is payable by a Seller
     pursuant to Section 4.4(a), the amount of such payment shall be reduced by
     any reduction of Taxes as a result of such audit or administrative or
     judicial proceeding (assuming all other items of deduction then available
     are realized first) with respect to the assets or business of any member of
     any Company Group or any German Branch for any period or partial period
     ending after the Closing Date("REDUCED TAXES"); PROVIDED, that if any such
     Reduced Taxes arise after the date on which payment is made by a Seller
     pursuant to Section 4.4(a), the applicable Company or the Purchaser shall
     pay over an amount equal to such Reduced Taxes promptly after such
     reduction in Taxes occurs. In the case of any refund received by, or
     Reduced Taxes realized by, a Company listed on Exhibit B-1 or any of such
     Company's Subsidiaries or Thermometrics Beijing, the refund or Reduced
     Taxes payable to the Sellers or the reduction to the amount payable by the
     Sellers in the case of Reduced Taxes shall be such amount multiplied by the
     Applicable Percentage and shall be paid by the Purchaser. Any dispute with
     respect to refunds or Reduced Taxes shall be resolved by the Third Party
     Accountants, and any such determination by the Third Party Accountants
     shall be final. The Purchaser and the Sellers agree to

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                                       22               Stock Purchase Agreement
<Page>

     cooperate, and the Purchaser agrees to cause each Company Group member and
     its other Affiliates to cooperate with the Sellers, with respect to
     claiming any refund or realizing the benefit of any Reduced Taxes referred
     to in this Section 4.4(d), including notifying the Sellers or the
     Purchaser, as the case may be, of the existence of any facts that would
     constitute a reasonable basis for claiming such a refund or Reduced Taxes,
     providing all relevant information available to the Sellers or the
     Purchaser (through any member of any Company Group or otherwise), as the
     case may be, with respect to any such claim, filing and diligently pursuing
     such claim (including by litigation, if appropriate) and, in the case of
     the party filing such a claim, consulting with the other party prior to
     agreeing to any disposition of such claim, provided that the Sellers shall
     not be obligated by the terms of this Section 4.4(d) to amend any Tax
     Return previously filed in order to claim a refund attributable to the
     carryback of a loss or credit incurred by any member of any Company Group
     in a taxable period after the Closing Date.

          (e)  COOPERATION. The Sellers and the Purchaser will, and will cause
     their respective Affiliates to, provide each other with such cooperation
     and information in their possession or to which they have reasonable access
     as either of them reasonably may request of the other in filing any return,
     amended return or claim for refund, determining a liability for Taxes or a
     right to a refund of Taxes, or participating in or conducting an audit or
     other proceeding in respect of Taxes. Without limiting the generality of
     the foregoing, the Purchaser shall, or shall cause each Company Group
     member to, use its reasonable best efforts accurately and timely to
     complete any tax information package or questionnaire that is customary and
     consistent with past practice submitted to it by any of the Sellers for the
     purpose of enabling such Seller to complete any Tax Return that such Seller
     is required to prepare pursuant to this Agreement. Each of the Purchaser
     and the Sellers shall retain all returns, schedules and work papers,
     records and other documents in its possession relating to Tax matters of
     any of the Company Group members or any German Branch for each taxable
     period first ending after the Closing Date and for all prior taxable
     periods until the later of (i) the expiration of the statute of limitations
     of the taxable periods to which - such returns and other documents relate,
     without regard to extension except to the extent notified by the other
     party in writing of such extensions for the respective Tax periods or (ii)
     six years following the due date (without extension) for such returns.
     After the Closing Date each Tax Return and report prepared or caused to be
     prepared by the Purchaser or any member of any Company Group with respect
     to any member of a Company Group or any German Branch which relates to any
     period that includes days on or before the Closing Date shall be subject to
     pre-filing review by the Sellers and, in the event of any disagreement
     between the Purchaser or any member of any Company Group, on the one hand,
     and any of the Sellers, on the other hand, such disagreement shall be
     resolved by the Third

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<Page>

     Party Accountants, and any such determination by the Third Party
     Accountants shall be final. The fees and expenses of the Third Party
     Accountants for services performed under this Section 4.4 shall be borne
     50% by the Purchaser and 50% by the Sellers. Unless otherwise agreed to by
     the parties, Tax Returns and reports subject to such pre-filing review plus
     a statement, in reasonable detail, showing the calculation supporting the
     Purchaser's determination with regard to the allocation of any Taxes
     reportable on any such Tax Return, shall be submitted by the Purchaser or
     any member of any Company Group to the Sellers at least 45 days prior to
     the due date (including extensions) of such return or report and the
     Sellers shall either complete their review or provide written comments on
     such return or report within 15 days of receipt of such return or report.

          (f)  AUDITS. Each of the Purchaser and the Sellers shall promptly
     notify the other in writing within ten days from its receipt of notice of
     (i) any pending or threatened U.S. federal, state or local or non-U.S. tax
     audits, inquiries or assessments of any member of any Company Group or any
     German Branch, so long as any taxable periods of such member of a Company
     Group or such German Branch ending on or prior to the Closing Date remain
     open, and (ii) any pending or threatened U.S. federal, state or local or
     non-U.S. tax audits, inquiries or assessments of the Purchaser or any of
     the Sellers which may affect the tax liabilities of any member of any
     Company Group or any German Branch for taxable periods ending on or prior
     to the Closing Date. The Sellers shall have the right to control the
     conduct and disposition of any tax audit, inquiry or administrative or
     court proceeding relating to any member of any Company Group or any German
     Branch for taxable periods ending on or prior to the Closing Date and to
     employ counsel of its choice at its expense and the Purchaser shall have
     the right to consult with the Seller during such proceedings at its own
     expense, provided that the Sellers shall not dispose of any such proceeding
     in a manner that would purport to bind the Purchaser or any member of any
     Company Group for taxable periods ending after the Closing Date without the
     prior written consent of the Purchaser, which consent shall not be
     unreasonably withheld. With respect to any tax audit, inquiry or
     administrative or court proceeding relating to any Straddle Return, such
     audit, inquiry or proceeding shall be controlled by the Purchaser, provided
     that the Purchaser shall (x) afford the Sellers and their tax advisers a
     reasonable opportunity to participate in the conduct of any administrative
     or judicial proceeding regarding or arising out of any audits, inquiries or
     assessments, including, without limitation, the right to participate in
     conferences with taxing authorities and to submit pertinent material in
     support of the Sellers' position, and (y) not accept any proposed
     adjustment or enter into any settlement or agreement in compromise which
     would result in a claim for indemnification against the Sellers pursuant
     to this Agreement without the prior written consent of the Sellers, which
     consent shall not be unreasonably withheld. The Purchaser agrees that it
     shall cooperate fully, and shall cause each member of

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                                       24               Stock Purchase Agreement
<Page>

     a Company Group to cooperate fully, with the Sellers and their counsel in
     the defense against or compromise of any claim in any proceeding controlled
     by the Sellers pursuant to this Section 4.4(f).

          (g)  CONDUCT OF BUSINESS. On the Closing Date, as to matters which
     could affect the Tax Returns of any member of any Company Group or any
     German Branch with respect to periods ending on or prior to the Closing
     Date, the Purchaser shall cause such Company Group member or German Branch
     to carry on its business only in the ordinary course in substantially the
     same manner as heretofore conducted, except as may be expressly required by
     applicable law or expressly required or expressly permitted by this
     Agreement.

          (h)  PAYMENT OF TRANSACTION-RELATED TAXES AND FEES. All transfer,
     sales, use and similar taxes and fees (including but not limited to
     notarial fees) arising out of the sale of the Shares, the Designated
     Receivables and the German Assets pursuant to this Agreement or any
     Additional Transfer Agreement shall be paid (or caused to be paid) by the
     Purchaser.

          (i)  TERMINATION OF TAX SHARING AGREEMENTS. Prior to the Closing, the
     Sellers shall terminate any Tax allocation, sharing, indemnification or
     similar agreement to which any of the Sellers, on the one hand, and any
     member of any Company Group or any German Branch, on the other hand, is a
     party.

          (j)  LIMITS ON INDEMNITY. No claim for indemnification pursuant to
     this Section 4.4 may be made after the 60th day following the expiration of
     the applicable statutes of limitations with respect to the tax liabilities
     in question, giving effect to any extension thereof. The Sellers'
     indemnification obligation under Section 4.4(a)(ii) shall be limited to the
     portion of the Purchase Price allocated on Exhibit C to the member of the
     Company Group whose liability for Taxes gives rise to such obligation, or
     if such member is not separately identified on Exhibit C, the portion of
     the Purchase Price allocated to such member as agreed to by the parties or
     the Third Party Accountants (if the parties cannot mutually agree).

          (k)  In the event of a conflict between Article 7 and this
     Section 4.4, this Section 4.4 shall be controlling with respect to Damages
     or claims relating to Taxes.

          4.5  NOTIFICATIONS; SUPPLEMENTS TO DISCLOSURES.

          (a)  From the date hereof to the Closing Date, the Sellers shall
     promptly notify the Purchaser in writing of (i) any representation or
     warranty made by them contained in this Agreement or any Additional
     Transfer Agreement becoming

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                                       25               Stock Purchase Agreement
<Page>

     untrue or inaccurate in any material respect or (ii) the failure by any
     Seller, any member of the Company Groups or the German Branches to comply
     with or satisfy in any material respect any covenant, condition or
     agreement to be complied with or satisfied by any of them under this
     Agreement or any Additional Transfer Agreement prior to the Closing, and
     such notice will be deemed to amend or supplement the Schedules. For
     purposes of determining the fulfillment of the condition precedent set
     forth in Section 6.4.1, no such amendment or supplement shall be given
     effect; for all other purposes, including, without limitation, Section
     7.2.1, each such amendment and supplement shall be given effect.

          (b)  From the date hereof to the Closing Date, the Purchaser shall
     promptly notify the Sellers in writing of (i) any representation or
     warranty made by it contained in this Agreement or any Additional Transfer
     Agreement becoming untrue or inaccurate in any material respect or (ii) the
     failure by the Purchaser to comply with or satisfy in any material respect
     any covenant, condition or agreement to be complied with or satisfied by
     such party under this Agreement or any Additional Transfer Agreement prior
     to the Closing. For purposes of determining the fulfillment of the
     condition precedent set forth in Section 6.3.1, no such amendment or
     supplement shall be given effect; for all other purposes, including,
     without limitation, Section 7.2.2, each such amendment and supplement shall
     be given effect.

          4.6  CONTACT WITH CUSTOMERS AND SUPPLIERS. None of the Purchaser or
     any of its agents, Affiliates, employees, directors or officers shall
     contact or communicate with any employees, customers, suppliers or
     licensors of any member of any Company Group or any German Branch in
     connection with the transactions contemplated hereby except with the prior
     written consent of Spirent plc, which consent may be conditioned upon the
     presence of an officer of one of the Sellers at any such meeting or
     conference, among other reasonable conditions as may be required by Spirent
     plc.

          4.7  PUBLICITY. No press release or public announcement related to
this Agreement or any Additional Transfer Agreement, or the transactions
contemplated hereby or thereby, shall be issued or made without the joint
approval of Spirent plc and the Purchaser, unless required by law (in the
reasonable opinion of counsel) or London Stock Exchange Limited, the United
Kingdom Panel on Mergers and Acquisitions or New York Stock Exchange rule, in
which case Spirent plc and the Purchaser shall use reasonable efforts to give
the other the opportunity to review such press release or announcement prior to
publication and, where practicable, agree to the form and wording of such
release or announcement.

          4.8  INTERCOMPANY ACCOUNTS. All intercompany accounts between any
member of any Company Group or any German Branch, on the one hand, and any
Seller

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                                       26               Stock Purchase Agreement
<Page>

or Non-Company Affiliate, on the other hand, shall be repaid, capitalized or
otherwise eliminated, in the manner indicated on Schedule 4.8 or another manner
that does not adversely affect the Purchaser, as of the close of business on the
business day immediately preceding the Closing Date, except (i) as set forth on
Schedule 4.8, (ii) for Designated Receivables and (iii) for trade payables and
receivables arising in the ordinary course of business.

          4.9  INDEMNIFICATION OF DIRECTORS AND OFFICERS. Following the Closing,
the Purchaser shall cause each Company Group to honor its obligations, if any,
to indemnify and advance defense costs to each present and former officer or
director of such Company Group pursuant to their respective by-laws (or
equivalent Organizational Document) and shall not permit the Organizational
Documents of any Company Group to be amended for a period of seven years in a
manner which adversely affects the indemnification rights, if any, of present
and former directors and officers of such Company Group, except as required by
applicable law. Each of the Sellers covenants for itself and its respective
successors and assigns that it shall not institute, or cause to be instituted,
any action or proceeding in any court or before any administrative agency or
before any tribunal against any of such present and former directors and
officers, in their capacity as such, with respect to any claims, liabilities,
actions or causes of action arising from actions occurring prior to the Closing,
other than any such actions arising in connection with the negotiation or
consummation of the transactions contemplated by this Agreement, the Additional
Transfer Agreements and the Ancillary Agreements.

          4.10 NON-COMPETITION.

          (a)  Prior to the second anniversary of the Closing Date, the Sellers
     shall not, and shall cause their Affiliates not to, directly or indirectly,
     own, manage, operate, or control any Person that provides temperature,
     humidity, pressure and gas sensors substantially similar to the products of
     such types currently provided by the Company Groups or the German Branches
     in the markets currently served by the Company Groups and the German
     Branches; PROVIDED that this Section 4.10 shall not prevent any of the
     Sellers or any of their respective Affiliates from (i) engaging in any
     business activity in which such Seller or Affiliate is engaged as of the
     date hereof; (ii) owning, solely as an investment, publicly-traded company
     securities so long as such Seller or Affiliate does not own or control, in
     the aggregate, more than 10% of any class of such securities; or (iii)
     acquiring or holding any interest in, or managing, operating or
     controlling, any Person that provides temperature, humidity, pressure and
     gas sensors substantially similar to the products of such types currently
     provided by the Company Groups or the German Branches in the markets
     currently served by the Company Groups and the German Branches if less than
     20% of the total revenues of such Person in the 12 months prior to such
     acquisition, or the commencement of the management, operation or control of
     such Person by any such Seller or Affiliate, arose out of or

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                                       27               Stock Purchase Agreement
<Page>

     were related to the provision of products and subsystems that sense
     temperature, humidity and pressure.

          (b) Prior to the second anniversary of the Closing Date, the Sellers
     shall not, and shall cause their Affiliates not to, (i) induce any employee
     of any member of a Company Group or any German Branch to leave such member
     of a Company Group or such German Branch or to accept any other employment
     or position, or (ii) assist any other entity in hiring any such employee.

          4.11 INSURANCE. The Sellers shall use commercially reasonable efforts
to keep, or cause to be kept, all insurance policies applicable to the Business
of the Company Groups and the German Branches currently in effect in full force
and effect through the close of business on the Closing Date.

          4.12 KOREAN JOINT VENTURES. As promptly as practicable after the date
hereof, the Purchaser shall execute and deliver written undertakings whereby it
agrees to be bound, subject to the consummation of the transaction contemplated
under this Agreement, by all of the terms and conditions of (a) the Joint
Venture Agreement, dated as of August 11, 1999, between Spirent B.V. (f/k/a
Bowthorpe - B.V.) and Partsnic Company Limited (f/k/a Daewoo Electronic
Components Company Limited) and (b) the Joint Venture Agreement, dated as - of
October 19, 2000, between Spirent B.V. and LG Electronics Inc., which
undertakings shall in each case be in form and substance reasonably satisfactory
to Partsnic Company Limited or LG Electronic Inc., as the case may be.

          4.13 GERMAN ASSETS; TAUNTON LEASE. At the Closing, (i) the Purchaser
and Spirent GmbH shall execute and deliver the German Asset Purchase Agreement
and the Dutch Asset Purchase Agreement and consummate the sale and purchase of
the German Assets; and (ii) Spirent plc shall, and shall cause Spirent
Components Limited to, execute and deliver an assignment and assumption
agreement whereby Spirent plc assigns, and Spirent Components Limited assumes,
the Lease, dated as of March 8, 1982 (the "TAUNTON LEASE"), between Spirent plc
and Crown Estate Commissioners relating to the property located at Crown
Industrial Estate (Site C), Priorswood Road, Taunton, UK, and Spirent plc and
Spirent Components Limited shall consummate such assignment and assumption; and
the Purchaser shall execute and deliver a guarantee of the lessee's obligations
under the Taunton Lease or provide such other assurances as Crown Estate
Commissioners may reasonably require for the complete and unconditional release
of Spirent plc and Spirent Components Limited from all obligations in connection
with the Taunton Lease.

          4.14 LOCAL PURCHASE AGREEMENTS. If reasonably requested by the Sellers
or the Purchaser, the Purchaser and the Sellers shall enter into a separate,
additional stock purchase agreement (each, a "LOCAL PURCHASE AGREEMENT") with
respect to the sale and

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                                       28               Stock Purchase Agreement
<Page>

purchase of the Shares of any Company organized in a non-U.S. jurisdiction,
PROVIDED that no such agreement shall contain any (i) representations and
warranties, covenants or conditions that are not also contained, in
substantially similar form, in this Agreement or (ii) provisions inconsistent
with the provisions of this Agreement.

          4.15 BANK ACCOUNTS. The Sellers shall, to the extent reasonably
practicable on or prior to the Closing Date, cause the Companies or their
Subsidiaries to withdraw and distribute to the Sellers, or apply to the payment
of indebtedness of such Companies or their Subsidiaries, by way of dividend or
otherwise, all cash in the bank accounts listed on Schedule 2.17.

          4.16 CHANGE OF NAME; DISCONTINUANCE OF USE OF "SPIRENT". Within
fifteen days following the Closing Date, the Purchaser shall change the names of
Spirent Korea Ltd., Spirent Components Limited and Spirent Sensing Inc. to
eliminate the word "Spirent" from such names and shall submit to the appropriate
governmental authorities or offices in complete and correct form all of the
filings required to reflect such changes in name. Within thirty days following
the Closing Date, the Purchaser shall cease using any stationery, signage,
equipment, invoices, receipts, forms, packaging, advertising and promotional
materials, product, training and service literature and materials, software or
other materials using the designation "Spirent" or any other designation
indicating an affiliation with any Seller or any Non-Company Affiliate.

          4.17 TRANSITIONAL SERVICES. Following the Closing Date, the Sellers
shall provide to the Company Groups and the German Branches the transitional
services specified in Schedule 4.17, on the terms specified in such Schedule.

          5.   EMPLOYEES AND EMPLOYEE BENEFIT PLANS.

          5.1  CONTINUATION OF BENEFITS.

          (a)  Each employee of any member of the Company Group and each former
     employee of any member of the Company Group entitled to any compensation,
     benefits or other payments arising in connection with such former
     employee's employment with any member of any Company Group shall be
     referred to as a "COMPANY EMPLOYEE." The term "Company Employee" shall also
     be deemed to include (i) any employee of the German Branches and (ii) the
     Sellers' employees listed on Schedule 5.1, each of whom devotes at least a
     majority of his or her working time to the performance of services for any
     member of any Company Group or any German Branch. As of the Closing Date,
     the Sellers shall terminate the employment of each of the Company Employees
     described in the preceding sentence who remain employed by the Sellers
     immediately prior to the Closing Date, and the Purchaser shall offer
     employment to all such employees and assume all employment agreements and
     severance

                                                            Amended and Restated
                                       29               Stock Purchase Agreement
<Page>

     liabilities in connection with such employees. Concurrently therewith, the
     Sellers shall assign to the Purchaser the employment agreements and
     severance liabilities in connection with such employees.

          (b)  From and for one year after the Closing, the Purchaser will, or
     will cause any Company or one of its Subsidiaries or the Purchaser's
     Subsidiaries, as applicable, to continue to provide each Company Employee
     with a salary or wage level and bonus opportunity, to the extent
     applicable, at least equal to that in effect on the Closing Date and with
     employee benefits and other terms and conditions of employment that are, in
     the aggregate, comparable to the benefits and terms and conditions provided
     to each such Company Employee by the Sellers, any Company or any of its
     Subsidiaries, as applicable, on the Closing with length of service with
     such Company or Subsidiary, up to the Closing Date, to be recognized by the
     Purchaser for all purposes, including, without limitation, for the purposes
     of the Purchaser's benefit plans (other than accrual of benefits). From and
     after the Closing, the Purchaser shall, or shall cause any Company or one
     of its Subsidiaries or one of the Purchaser's Subsidiaries, as applicable,
     to honor, pay, perform, and satisfy any and all liabilities, obligations
     and responsibilities to or in respect of each Company Employee arising
     under the terms of or in connection with any Plan, employment agreement and
     collective bargaining agreement maintained by any member of the Company
     Groups or otherwise assigned to the Purchaser as in effect immediately
     prior to the Closing. Nothing in this Section 5.1 shall preclude the
     Purchaser from, at any time following the Closing, terminating the
     employment of any Company Employee; PROVIDED that if such termination
     occurs prior to one year following the Closing Date and such termination is
     not for cause, any such terminated Company Employee receives severance and
     other termination benefits upon or in connection with such termination in
     an amount which is at least equal to the severance and other termination
     benefits which would have been provided to such Company Employee if his or
     her employment had been terminated for the same reason immediately prior to
     the Closing, all of which benefits are described on Schedules 2.10(a) and
     2.10(b).

          5.2  401(k) PLAN. As soon as practicable after the Closing Date,
Company Employees who were participants in the 401(k) Retirement and Profit
Sharing Plan for the Employees of the U.S. Affiliates of Spirent plc (the
"SELLER 401(k) PLAN") and who are actively employed on the Closing Date shall
commence participation in a tax-deferred savings plan maintained by the
Purchaser (the "PURCHASER 401(k) PLAN"). As soon as practicable following the
later of (i) the expiration of a 30-day period following the date of filing of
any required notices with the IRS by both the Sellers and the Purchaser and (ii)
delivery to the Sellers of a favorable determination letter from the IRS
regarding the qualified status of the Purchaser 401(k) Plan, the Sellers shall
cause the transfer from the Seller 401(k) Plan to the Purchaser 401(k) Plan of
the value of the full account balances

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                                       30               Stock Purchase Agreement
<Page>

of such employees in cash on the date of transfer (which account balances will
have been credited with appropriate earnings attributable to the period from the
Closing Date to the date of transfer described herein); PROVIDED that to the
extent that any loan had been extended to any such Company Employee participants
under the Seller 401(k) Plan prior to the Closing Date, such loans and any
promissory notes or other documents evidencing such loans shall be transferred
to the Purchaser 401(k) Plan and shall be valued based on the outstanding
principal and interest due thereunder. The Sellers and the Purchaser shall
cooperate to the extent necessary and reasonable to facilitate such transfer and
loan payments. From and after such transfer from the Seller 401(k) Plan to
Purchaser 401(k) Plan in accordance with the provisions of this Section 5.2, the
Purchaser 401(k) Plan shall be solely responsible for the provision of all
benefits to the Company Employees previously provided under the Seller 401(k)
Plan. Prior to the plan-to-plan transfer, the Sellers shall make all matching
contributions with respect to such employees that are required to be made on
account of any period prior to the Closing Date.

          5.3  UK PENSION SCHEMES. The Sellers and the Purchaser agree to comply
with the agreements relating to the transfer of United Kingdom employee benefits
plans set forth on Exhibit E hereto.

          5.4  SELLER RETAINED LIABILITIES. The Sellers shall retain all
liabilities related to equity based awards granted to employees of the Company
Groups under any of the Sellers' equity based compensation plans.

          6.   CONDITIONS PRECEDENT.

          6.1  GENERAL. The respective obligations set forth herein of the
Sellers and the Purchaser to consummate the sale and purchase of the Shares and
the Designated Receivables at the Closing shall be subject to the fulfillment,
on or before the Closing Date, in the case of the Sellers, of the conditions set
forth in Sections 6.2 and 6.3, and in the case of the Purchaser, of the
conditions set forth in Sections 6.2 and 6.4.

          6.2  CONDITIONS TO OBLIGATIONS OF BOTH PARTIES.

          6.2.1 HSR ACT, ETC. To the extent notifications or applications are
required to be filed under the HSR Act, the waiting period under the HSR Act
shall have been terminated or expired. The notifications or applications that
are required to be filed prior to the Closing under the antitrust, competition
or comparable laws of any non-U.S. jurisdiction and that are listed on Schedule
3.2(b) shall have been filed. The consents or approvals of any governmental
authority that are required to be obtained prior to the Closing under the
antitrust, competition or comparable laws of any non-U.S. jurisdiction and that
are listed and marked with an asterisk on Schedule 3.2(b) shall have been
obtained.

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                                       31               Stock Purchase Agreement
<Page>

          6.2.2 CONSENTS. All governmental and third party consents listed on
Schedule 6.2.2 shall have been obtained.

          6.2.3 NO INJUNCTION. There shall not be in effect any injunction or
other order issued by a court of competent jurisdiction, U.S. or non-U.S.,
restraining or prohibiting the consummation of the transactions contemplated by
this Agreement.

          6.2.4 ALL SHARES PURCHASED AND SOLD. Except as provided in Section
1.4, the Purchaser shall be purchasing and the Sellers shall be selling all of
the Shares and the Designated Receivables at the Closing.

          6.2.5 GERMAN ASSET SALE. The transactions contemplated by the German
Asset Purchase Agreement and the Dutch Asset Purchase Agreement shall have been
consummated in accordance with the terms and conditions specified therein.

          6.3  CONDITIONS TO OBLIGATIONS OF THE SELLERS.

          6.3.1 REPRESENTATIONS AND WARRANTIES OF THE PURCHASER. The
representations and warranties in Section 3 shall be true and correct when made
and at and as of the Closing Date with the same effect as though made at and as
of such time, with such exceptions as are not in the aggregate material. The
Purchaser shall have duly performed and complied in all material respects with
all agreements contained herein required to be performed or complied with by it
at or before the Closing.

          6.3.2 OFFICER'S CERTIFICATE. The Purchaser shall have delivered to the
Sellers a certificate, dated the Closing Date and signed by an authorized senior
officer, as to the fulfillment of the conditions set forth in Section 6.3.1.

          6.3.3 RELEASES OF GUARANTIES AND BONDS. The relevant Sellers and
Non-Company Affiliates shall have been completely and unconditionally released
from any and all obligations in connection with the Guaranties and Bonds listed
on Schedule 4.1.

          6.4  CONDITIONS TO OBLIGATIONS OF THE PURCHASER.

          6.4.1 REPRESENTATIONS AND WARRANTIES OF THE SELLER. The
representations and warranties in Section 2 shall be true and correct when made
and at and as of the Closing Date with the same effect as though made at and as
of such time, ignoring for this purpose all qualifications as to knowledge,
materiality or Material Adverse Effect in such representations and warranties
(other than with respect to Section 2.15(y)), except for any and all failures of
such representations and warranties to be correct in all respects as of the
Closing Date (with all such failures considered in the aggregate) as would not
have a Material Adverse Effect. Each Seller shall have duly performed and
complied in

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                                       32               Stock Purchase Agreement
<Page>

all material respects with all agreements contained herein required to be
performed or complied with by it at or before the Closing.

          6.4.2 OFFICER'S CERTIFICATE. The Sellers shall have delivered to the
Purchaser a certificate, dated the Closing Date and signed by an authorized
senior officer of each Seller, as to the fulfillment of the conditions set forth
in Section 6.4.1.

          6.4.3 RESIGNATIONS. The directors and officers of the Companies or
their Subsidiaries, as the case may be, who have been specified in a notice
delivered by the Purchaser to Spirent plc at least ten days prior to the Closing
shall have submitted their resignations from the Boards of Directors of such
Companies or such Subsidiaries and as officers of such Companies or such
Subsidiaries, as the case may be, effective as of the Closing Date, in each case
without liability to any member of any Company Group.

          6.4.4 TAX CERTIFICATE. Spirent International shall have delivered to
the Purchaser the certificate described in Treasury Regulation Section
1.1445-2(b)(2)(i) to the effect that it is not a foreign person within the
meaning of Section 1445 of the Code.

          6.4.5 DISCHARGE OF CERTAIN OBLIGATIONS. All of the obligations of any
member of any Company Group to satisfy overdrafts on the accounts listed in
Schedule 2.17 shall have been paid or discharged in full.

          7.   INDEMNIFICATION.

          7.1  SURVIVAL OF REPRESENTATIONS AND WARRANTIES.

          (a)  The representations and warranties made by the Sellers and the
     Purchaser in this Agreement shall survive the Closing and expire upon the
     first anniversary of the Closing Date, except that the representations and
     warranties made in or pursuant to Sections 2.1, 2.4, 2.5(b), 3.1 and 3.5
     shall survive the Closing without limitation.

          (b)  Any claim for indemnification under this Section 7 with respect
     to such representations and warranties must be brought in accordance with
     Section 7.2.3 prior to the expiration of the applicable representation and
     warranty pursuant to Section 7.1(a).

          7.2  INDEMNIFICATION.

          7.2.1 BY THE SELLERS. From and after the Closing, the Sellers, jointly
and severally, agree to indemnify and hold harmless the Purchaser, each
Affiliate of the Purchaser (other than the Companies and their Subsidiaries) and
each director, officer and employee of the Purchaser or any of its Affiliates
(collectively, the "PURCHASER INDEMNITEES") from and against any loss,
liability, damage (exclusive of any

                                                           Amended and Restated
                                       33               Stock Purchase Agreement
<Page>

consequential, indirect, speculative or punitive damages) or cost, including
reasonable attorneys' fees and other costs and expenses (collectively,
"DAMAGES"), incurred or sustained by the Purchaser Indemnitees as a result of
the breach by the Sellers of any covenant set forth in this Agreement or,
subject to Section 7.1, any representation or warranty set forth in this
Agreement, other than any Damages relating to Taxes which shall be governed
exclusively by Section 4.4, PROVIDED that there shall not be any duplicative
payments or indemnities by the Sellers.

     The rights of the Purchaser Indemnitees to indemnification under this
Section 7 shall be limited as follows:

          (a)  The amount of any Damages incurred or sustained by the Purchaser
     Indemnitees shall be reduced by the net amount of any Tax benefits actually
     realized by the Purchaser or any of its Affiliates by reason of such
     Damages in the year such Damages were incurred or sustained or any prior
     year or any of the succeeding five years following the year the Damages
     were incurred or sustained (assuming all other items of deduction of the
     Purchaser or such Affiliate then available to the Purchaser or such
     Affiliate are realized first). If any such Tax benefit is realized after
     the date payment is made by a Seller pursuant to Section 7.2.1, the
     Purchaser Indemnitees shall pay over an amount equal to such Tax benefit
     promptly after such Tax benefit is realized.

          (b)  The amount of any Damages incurred or sustained by the Purchaser
     Indemnitees shall be reduced by the net amount the Purchaser Indemnitees
     recover (after deducting all attorneys' fees, expenses and other costs of
     recovery) from any insurer or other party liable for such Damages, and the
     Purchaser, on behalf of the Purchaser Indemnitees, shall use reasonable
     efforts to effect any such recovery.

          (c)  The Purchaser Indemnitees shall be entitled to indemnification
     under this Section 7 for breaches of representations and warranties (i)
     with respect to any individual claim or group of related claims, only if
     the amount of Damages (reduced as provided in paragraphs (a), (b) and (e)
     of this Section 7.2.1) exceeds US$15,000 and (ii) with respect to all
     claims, only to the extent that the aggregate amount of Damages for such
     claims (reduced as provided in paragraphs (a), (b) and (e) of this Section
     7.2.1) exceeds 3% of the Purchase Price (as adjusted) and then only for the
     amount of such excess. In no event shall the Purchaser Indemnitees be
     entitled to indemnification exceeding 10% of the Purchase Price (as
     adjusted) in the aggregate.

          (d)  The Purchaser Indemnitees shall not be entitled to make a claim
     for indemnification under this Section 7 for any breach by any Seller of
     any covenant,

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                                       34               Stock Purchase Agreement
<Page>

     representation or warranty set forth in this Agreement if the Purchaser had
     actual knowledge of such breach prior to the Closing.

          (e)  The parties acknowledge that, pursuant to this Agreement, the
     Purchaser will acquire the respective Applicable Percentages of the total
     equity interests in each Company listed on Exhibit B-1 and a 90% equity
     interest in Thermometrics Beijing. The Sellers' obligation to indemnify the
     Purchaser Indemnitees for Damages incurred or sustained by them in
     connection with any Company listed on Exhibit B-1 or Thermometrics Beijing
     shall be limited to an amount equal to the product of the amount of Damages
     (reduced as provided in paragraphs (a) and (b) above) incurred or sustained
     by such entity multiplied by the Applicable Percentage in respect of such
     entity.

          7.2.2 BY THE PURCHASER. From and after the Closing, the Purchaser
agrees to indemnify and hold harmless the Sellers, each Non-Company Affiliate
and each director, officer or employee of any of the foregoing (collectively,
the "SELLER INDEMNITEES") from and against any Damages incurred or sustained by
the Seller Indemnitees as a result of or arising out of or under (i) the breach
by the Purchaser of any covenant, representation or warranty set forth in this
Agreement, (ii) the German Liabilities, (iii) the operation by the Purchaser of
the Business of the German Branches or the Purchaser's ownership, operation or
use of the German Assets following the Closing Date, (iv) the Taunton Lease, (v)
the employment, employment agreements and severance liabilities relating to the
employees of the German Branches and the employees listed on Schedule 5.1, and
(vi) any of the Guaranties and Bonds, PROVIDED that the Seller Indemnitees shall
not be entitled to indemnification pursuant to the foregoing clauses (ii) - (v)
in respect of any Damages to the extent the Purchaser is entitled to
indemnification therefor pursuant to Section 7.2.1, and PROVIDED, FURTHER, that
there shall not be any duplicative payments or indemnities by the Purchaser.

     The rights of the Seller Indemnitees to indemnification under this Section
7 shall be limited as follows:

          (a)  The amount of any Damages incurred by the Seller Indemnitees
     shall be reduced by the net amount of the Tax benefits actually realized by
     the Sellers or any of their Affiliates by reason of such Damages in the
     year such Damages were incurred or sustained or any prior year or any of
     the succeeding five years following the year such Damages were incurred or
     sustained (assuming all other items of deduction of the Sellers or such
     Affiliate then available to the Purchaser or such Affiliate are realized
     first). If any such Tax benefit is realized after the date payment is made
     by the Purchaser pursuant to Section 7.2.2, the Seller Indemnitees shall
     pay over an amount equal to such Tax benefit promptly after such Tax
     benefit is realized.

                                                           Amended and Restated
                                       35               Stock Purchase Agreement
<Page>

          (b)  The amount of any Damages incurred by the Seller Indemnitees
     shall be reduced by the net amount the Seller Indemnitees recover (after
     deducting all attorneys' fees, expenses and other costs of recovery) from
     any insurer or other party liable for such Damages, and the Sellers, on
     behalf of the Seller Indemnitees, shall use reasonable efforts to effect
     any such recovery.

          (c)  The Seller Indemnitees shall be entitled to indemnification under
     this Section 7 for breaches of representations and warranties (i) with
     respect to any individual claim or group of related claims, only if the
     amount of Damages (reduced as provided in paragraphs (a), (b) and (d) of
     this Section 7.2.2) exceeds US$15,000 and (ii) with respect to all claims,
     only to the extent that the aggregate amount of Damages for such claims
     (reduced as provided in paragraphs (a), (b) and (d) of this Section 7.2.2)
     exceeds 3% of the Purchase Price (as adjusted) and then only for the amount
     of such excess. In no event shall the Seller Indemnitees be entitled to
     indemnification exceeding 10% of the Purchase Price (as adjusted) in the
     aggregate.

          (d)  The Seller Indemnitees shall not be entitled to make a claim for
     indemnification under this Section 7 for any breach by the Purchaser of any
     covenant, representation or warranty set forth in this Agreement if the
     Sellers had actual knowledge of such breach prior to the Closing.

          7.2.3 INDEMNIFICATION PROCEDURES. A party entitled to indemnification
under Section 7 shall herein be referred to as an "INDEMNITEE." A party
obligated to indemnify an Indemnitee under Section 7 shall herein be referred to
as an "INDEMNITOR."

          (a)  THIRD PARTY CLAIMS. Within ten business days after an Indemnitee
     receives notice of any third party claim or the commencement of any action
     by any third party which such Indemnitee reasonably believes may give rise
     to a claim for indemnification from an Indemnitor hereunder, such
     Indemnitee shall, if a claim in respect thereof is to be made against an
     Indemnitor under Section 7, notify such Indemnitor in writing in reasonable
     detail of such claim or action and include with such notice copies of all
     notices and documents (including court papers) served on or received by the
     Indemnitee from such third party. Upon receipt of such notice, the
     Indemnitor shall be entitled to participate in such claim or action, to
     assume the defense thereof with counsel reasonably satisfactory to the
     Indemnitee, and to settle or compromise such claim or action, PROVIDED that
     if the Indemnitee has elected to be represented by separate counsel
     pursuant to the proviso to the following sentence, such settlement or
     compromise shall be effected only with the consent of the Indemnitee, which
     consent shall not be unreasonably withheld or delayed. After notice to the
     Indemnitee of the Indemnitor's election to assume the defense of such claim
     or action, the Indemnitor shall not be liable to the Indemnitee under
     Section 7 for any legal or

                                                           Amended and Restated
                                       36               Stock Purchase Agreement
<Page>

     other expenses subsequently incurred by the Indemnitee in connection with
     the defense thereof other than reasonable costs of investigation, PROVIDED
     that the Indemnitee shall have the right to employ counsel to represent it
     if either (x) such claim or action involves remedies other than monetary
     damages and such remedies, in the Indemnitee's reasonable judgment, could
     have a material adverse effect on such Indemnitee or (y) the Indemnitee may
     have available to it one or more defenses or counterclaims which are
     inconsistent with one or more defenses or counterclaims which may be
     alleged by the Indemnitor, and in any such event the fees and expenses of
     such separate counsel shall be paid by the Indemnitee. If the Indemnitor
     does not elect to assume the defense of such claim or action within 45 days
     of the Indemnitee's delivery of notice of such a claim or action, the
     Indemnitee shall be entitled to assume the defense thereof. Unless it has
     been conclusively determined through a final judicial determination (or
     settlement tantamount thereto) that the Indemnitor is not liable to the
     Indemnitee under this Section 7.2.3, the Indemnitee shall act reasonably
     and in accordance with its good faith business judgment with respect to
     such defense, and shall not settle or compromise any such claim or action
     without the consent of the Indemnitor, which consent shall not be
     unreasonably withheld or delayed. The parties hereto agree to render to one
     another such assistance as may reasonably be requested in order to insure
     the proper and adequate defense of any such claim or action, including
     making employees available on a mutually convenient basis to provide
     additional information and explanation of any relevant materials or to
     testify at any proceedings relating to such claim or action.

          (b)  OTHER CLAIMS. Within ten business days after an Indemnitee
     sustains any Damages not involving a third party claim or action which such
     Indemnitee reasonably believes may give rise to a claim for indemnification
     from an Indemnitor hereunder, such Indemnitee shall deliver notice of such
     claim to the Indemnitor, specifying with reasonable detail the basis on
     which indemnification is being asserted and the amount of such Damages.

          7.2.4 EXCLUSIVITY OF INDEMNIFICATION PROVISION. Except as otherwise
expressly set forth in this Agreement, the indemnities provided for in this
Section 7 (including without limitation the survival periods contained in
Section 7.1 and the limitations on indemnification contained in this Section
7.2) shall be the sole and exclusive remedy for monetary damages of the parties
hereto after the Closing for any inaccuracy of any representation or warranty
contained in this Agreement, any failure or breach of any covenant, obligation,
condition or agreement contained in this Agreement or any Additional Transfer
Agreement or any loss, liability, damage or cost arising or incurred in
connection with or as a result of the negotiation, execution, delivery or
consummation of the transactions contemplated by this Agreement and the
Additional Transfer Agreements or arising out or resulting from the ownership of
the Company Groups by the Purchaser. The indemnification provisions contained in
this Agreement

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                                       37               Stock Purchase Agreement
<Page>

shall supersede any indemnification obligations set forth in any Additional
Transfer Agreement.

          7.2.5 RECOVERIES. If at any time subsequent to the receipt by an
Indemnitee of an indemnity payment under this Section 7, such Indemnitee (or any
Affiliate thereof) receives any recovery, settlement or other similar payment (a
"RECOVERY") with respect to the Damages for which it received such indemnity
payment, such Indemnitee shall promptly pay to the Indemnitor an amount equal to
the amount of such Recovery, less any expense incurred by such Indemnitee (or
its Affiliates) in connection with such Recovery, but in no event shall any such
payment exceed the amount of such indemnity payment.

          8.   [Reserved.]

          9.   GENERAL PROVISIONS.

          9.1  MODIFICATION; WAIVER. This Agreement may be modified only by a
written instrument executed by the parties hereto. Any of the terms and
conditions of this Agreement may be waived in writing at any time on or prior to
the Closing Date by the party or parties entitled to the benefits thereof.

          9.2  ENTIRE AGREEMENT. This Agreement, including the Schedules hereto
(which are hereby incorporated by reference and made a part hereof), the
Additional Transfer Agreements and the Ancillary Agreements constitute the
entire agreement of the parties with respect to the subject matter hereof and
supersede all other prior agreements, understandings, documents, projections,
financial data, statements, representations and warranties, oral or written,
express or implied, between the parties hereto and their respective Affiliates,
representatives and agents in respect of the subject matter hereof, except that
none of this Agreement, the Additional Transfer Agreements or the Ancillary
Agreements supersedes the Confidentiality Agreement, the terms and conditions of
which the parties hereto expressly reaffirm.

          9.3  CERTAIN LIMITATIONS. It is the explicit intent and understanding
of each of the parties hereto that no party nor any party's Affiliates,
representatives or agents is making any representation or warranty whatsoever in
connection with the transactions contemplated hereby and by the Additional
Transfer Agreements, oral or written, express or implied, other than those set
forth in Sections 2 and 3 of this Agreement and neither the Sellers, on the one
hand, nor the Purchaser, on the other hand, are relying on any other statement,
representation or warranty, oral or written, express or implied, made by the
other parties or such other parties' Affiliates, representatives or agents,
including, without limitation, any such statement, representation or warranty
contained in any offering memorandum or any information, document or material
made available to the Purchaser or its Affiliates, representatives or agents in
certain "data rooms", management

                                                           Amended and Restated
                                       38               Stock Purchase Agreement
<Page>

presentations or any other form in expectation of the transactions contemplated
by this Agreement and the Additional Transfer Agreements, except for the
representations and warranties set forth in such Sections 2 and 3. EXCEPT AS
OTHERWISE SPECIFICALLY SET FORTH IN THIS AGREEMENT, THE PARTIES EXPRESSLY
DISCLAIM ANY IMPLIED WARRANTY OR REPRESENTATION. The parties agree that this is
an arm's length transaction in which the parties' undertakings and obligations
are limited to the performance of their obligations under this Agreement, the
Additional Transfer Agreements and the Ancillary Agreements. The Purchaser
acknowledges that it is a sophisticated investor, that it has undertaken a full
investigation of the Business of the Company Groups and the German Branches, and
that it has only a contractual relationship with the Sellers, based solely on
the terms of this Agreement, and that there is no special relationship of trust
or reliance between any of them and any Seller.

          9.4  TERMINATION.

          (a)  This Agreement may be terminated: (i) at any time prior to the
     Closing Date by mutual consent of the Purchaser and Spirent plc, or (ii) by
     the Purchaser or Spirent plc, if the Closing shall not have taken place on
     or before the date that is 120 days following the date hereof, or such
     later date as the parties may have agreed to in writing, PROVIDED that the
     non-occurrence of the Closing is not attributable to a breach of the terms
     hereof by the party seeking termination, or (iii) by either the Purchaser
     or Spirent plc by written notice to the other party if any event, fact or
     condition shall occur or exist that shall have made it impossible to
     satisfy a condition precedent to the terminating party's obligations
     (including any Seller's obligations, if Spirent plc is the terminating
     party) to consummate the transactions contemplated by this Agreement, and
     such event, fact or condition shall not have been cured within thirty days
     after the non-terminating party is made aware of such event, fact or
     condition, unless the occurrence or existence of such event, fact or
     condition shall be due to the failure of the terminating party to perform
     or comply with any of the agreements or covenants hereof to be performed or
     complied with by such party prior to the Closing.

          (b)  In the event of termination by Spirent plc or the Purchaser
     pursuant to this Section 9.4, written notice thereof shall forthwith be
     given to the other party and the transactions contemplated by this
     Agreement shall be terminated without further action by either party. If
     the transactions contemplated by this Agreement are terminated as provided
     herein:

               (i) the Purchaser shall return to the Sellers all documents and
          other materials received from the Sellers and their respective
          Affiliates and agents relating to the transactions contemplated
          hereby, whether obtained before or after the execution hereof, and all
          copies of such documents and other materials; and the Purchaser shall
          return to the Sellers or destroy all

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                                       39               Stock Purchase Agreement
<Page>

          materials developed by the Purchaser or any of its Affiliates or
          agents from any such documents or other materials; and

               (ii) all confidential information received by the Purchaser with
          respect to the Sellers and their respective Affiliates shall be
          treated in accordance with the terms of the Confidentiality Agreement,
          which shall remain in full force and effect notwithstanding the
          termination of this Agreement.

          (c)  If this Agreement is terminated as provided in this Section 9.4,
     this Agreement and each Additional Transfer Agreement shall immediately
     become null and void and of no further force or effect without any further
     action by any of the parties hereto or thereto, except that the
     Confidentiality Agreement, Section 4.7 hereof relating to publicity, and
     Section 9.5 relating to certain expenses shall survive the termination of
     this Agreement. Nothing in this Section 9.4 shall be deemed to release any
     party from any liability for any breach by such party of the terms and
     provisions of this Agreement or to impair the right of any party to compel
     specific performance by any other party of its obligations under this
     Agreement.

          9.5  EXPENSES. Except as expressly provided herein, whether or not the
transactions contemplated herein shall be consummated, each party shall pay its
own expenses incident to the preparation and performance of this Agreement and
the Additional Transfer Agreements; PROVIDED that the Purchaser shall be
responsible for all filing fees in connection with the filings required by the
HSR Act.

          9.6  FURTHER ACTIONS. Each party shall execute and deliver such
certificates and other documents and take such other actions as may reasonably
be requested by the other party in order to consummate or implement the
transactions contemplated hereby.

          9.7  POST-CLOSING ACCESS. In connection with any matter relating to
any period prior to, or any period ending on, the Closing, the Purchaser shall,
upon the request and at the expense of the Sellers, permit any Seller and its
representatives full access at all reasonable times to the books, records and
personnel of the Companies and their Subsidiaries, and the Purchaser shall
execute (and shall cause the Companies or their successors and their respective
Subsidiaries to execute) such documents as such Seller may reasonably request to
enable such Seller to file any required reports relating to the Companies or any
of their Subsidiaries, to defend any litigation involving such Seller or any
Non-Company Affiliate or otherwise for a valid business purpose (in each case,
other than in respect of Taxes, which shall be governed by Section 4.4);
provided that the Sellers and any of their representatives adhere to whatever
procedures the Purchaser reasonably requests to safeguard confidential,
non-public or privileged information relating to the Purchaser, its Affiliates
or any member of the Company Groups or German

                                                           Amended and Restated
                                       40               Stock Purchase Agreement
<Page>

Branches. The Purchaser shall not dispose of such books and records during the
seven-year period beginning with the Closing Date without the Sellers' consent,
which shall not be unreasonably withheld. Following the expiration of such
seven-year period, the Purchaser may dispose of such books and records at any
time upon giving 60 days' prior written notice to the Sellers, unless a Seller
agrees to take possession of such books and records within 60 days from the date
of delivery of such notice at no expense to the Purchaser.

          9.8  NOTICES. All notices, requests, demands and other communications
hereunder shall be in writing and shall be deemed to have been duly given or
made as follows: (a) if sent by registered or certified mail in the United
States return receipt requested, upon receipt; (b) if sent by reputable
overnight air courier (such as DHL or Federal Express), two business days after
mailing; (c) if sent by facsimile transmission, with a copy mailed on the same
day in the manner provided in (a) or (b) above, when transmitted and receipt is
confirmed by telephone; or (d) if otherwise actually personally delivered, when
delivered and shall be delivered as follows:

               if to any of the Sellers, to such Seller:

                       c/o Spirent plc
                       Spirent House
                       Crawley Business Quarter
                       Fleming Way
                       Crawley, West Sussex RH10 2QL
                       Facsimile: 44 1293 76 7677
                       Attention: General Counsel

               with a copy to:

                       Debevoise & Plimpton
                       919 Third Avenue
                       New York, New York 10022
                       Facsimile: (212) 909-6836
                       Attention: Robert F. Quaintance, Jr.

               if to the Purchaser:

                       General Electric Company
                       41 Woodford Avenue
                       Plainville, Connecticut 06062
                       Facsimile: (860) 747-7079
                       Attention: Senior Counsel, Transactions

                                                        Amended and Restated
                                    41               Stock Purchase Agreement
<Page>

               with a copy to:

                       King & Spalding
                       1185 Avenue of the Americas
                       New York, New York 10036-4003
                       Faxsimile: (212) 556-2222
                       Attention: E. William Bates, II, Esq.

or to such other address or to such other Person as any party hereto shall have
last designated by notice to the other parties.

          9.9  ASSIGNMENT. This Agreement shall be binding upon and inure to the
benefit of the parties hereto and their respective successors and assigns,
PROVIDED that any assignment, by operation of law or otherwise, by any party
hereto shall require the prior written consent of the other parties and any
purported assignment or other transfer without such consent shall be void and
unenforceable; and PROVIDED FURTHER, however, that the Purchaser may assign or
transfer this Agreement in whole or in part to any of its Affiliates without
such consent, PROVIDED that the Purchaser shall remain, and all such assignees
and transferees shall be, jointly and severally liable for the obligations of
the Purchaser under this Agreement.

          9.10 NO THIRD PARTY BENEFICIARIES. Except as provided in Sections 4.9,
5 and 7, nothing in this Agreement shall confer any rights upon any Person which
is not a party or a successor or permitted assignee of a party to this
Agreement.

          9.11 COUNTERPARTS. This Agreement may be executed in counterparts,
each of which together shall constitute one and the same instrument.

          9.12 INTERPRETATION; DISCLOSURE SCHEDULES.

          (a)  The section headings in this Agreement are for convenience of
     reference only and shall not be deemed to alter or affect the meaning or
     interpretation of any provision hereof.

          (b)  The disclosure of any matter in any Schedule shall be deemed to
     be a disclosure for all purposes of this Agreement to which the relevance
     of such matter is reasonably apparent. Because of the different
     jurisdictions in which the Companies, their Subsidiaries and the German
     Branches are located and because of the different management teams having
     day-to-day responsibility for the operations of the Companies, their
     Subsidiaries and the German Branches, information contained in the
     Schedules was collected and is organized in separate sets, as indicated in
     the Table of Contents included in the Schedules. References in this
     Agreement to a particular Schedule (such as "Schedule 2.1") shall be deemed
     to refer collectively to all of the Schedules so designated. The fact that
     a

                                                           Amended and Restated
                                       42               Stock Purchase Agreement
<Page>

     particular group of Companies, Subsidiaries of Companies or German Branches
     is referred to in a set of Schedules shall not be deemed to limit the
     disclosures contained in such set of Schedules to such Companies,
     Subsidiaries or German Branches.

          Although the Sellers have endeavored to prepare the Schedules in a
     consistent manner, some of the Schedules differ in format or style
     according to local practice in the jurisdictions where particular
     Companies, their Subsidiaries or German Branches are located. The
     disclosure of any matter in any Schedule shall expressly not be deemed to
     constitute an admission by the Sellers, or to otherwise imply, that any
     such matter is material for the purposes of this Agreement or that any
     other Schedule (or set of Schedules) is incomplete by virtue of the
     omission of such disclosure. Except for information that is required by
     this Agreement to be included in the Schedules, the failure of any
     information contained in the Schedules to be true and correct shall not
     constitute a breach of any representation or warranty or other provision
     contained in this Agreement and the Sellers shall have no liability for
     such failure.

          (c)  In addition to the particular items set forth in the Schedules,
     the contents of this Agreement, each Additional Transfer Agreement and all
     transactions referred to herein or therein are disclosed or deemed
     disclosed to the Purchaser.

          9.13 GOVERNING LAW. This Agreement shall be construed, performed and
enforced in accordance with the laws of the State of New York, without regard to
the conflicts of law principles of such state.

          9.14 CONSENT TO JURISDICTION, ETC.

          (a)  Each of the parties hereto hereby irrevocably and unconditionally
     submits, for itself and its property, to the exclusive jurisdiction of any
     New York State court or federal court of the United States of America
     sitting in New York City, and any appellate court from any thereof, in any
     action or proceeding arising out of or relating to this Agreement, the
     Additional Transfer Agreements or the transactions contemplated hereby or
     thereby or for recognition or enforcement of any judgment relating thereto;
     and each of the parties hereto hereby irrevocably and unconditionally
     agrees that all claims in respect of any such action or proceeding may be
     heard and determined in such New York State court or, to the extent
     permitted by law, in such federal court. Each of the parties hereto agrees
     that a final judgment in any such action or proceeding shall be conclusive
     and may be enforced in other jurisdictions by suit on the judgment or in
     any other manner provided by law.

                                                           Amended and Restated
                                       43               Stock Purchase Agreement
<Page>

          (b)  Each of the parties hereto hereby irrevocably and unconditionally
     waives, to the fullest extent it may legally and effectively do so, any
     objection which it may now or hereafter have to the laying of venue of any
     suit, action or proceeding arising out of or relating to this Agreement,
     the Additional Transfer Agreements or the transactions contemplated hereby
     or thereby in any New York State or federal court. Each of the parties
     hereto hereby irrevocably waives, to the fullest extent permitted by law,
     the defense of an inconvenient forum to the maintenance of such action or
     proceeding in any such court.

          (c)  Each party to this Agreement irrevocably consents to service of
     process in the manner provided for notices in Section 9.8. Nothing in this
     Agreement will affect the right of any party to this Agreement to serve
     process in any other manner permitted by law.

          9.15 TAX TREATMENT OF INDEMNITY PAYMENTS. Each Seller, on the one
hand, and the Purchaser, on the other hand, agree (i) to treat any payment
pursuant to Section 1.4 and any indemnity payment made pursuant to Section 4.4
or Section 7.2 as an adjustment to the Purchase Price for all Tax purposes
unless otherwise required by law and (ii) to allocate the Purchase Price among
the Shares of each Company, the Designated Receivables and the German Assets as
set forth on Exhibit C, as the same may have been amended pursuant to Section
1.4 and modified pursuant to clause (i) of this Section 9.15, for all Tax
purposes unless otherwise required by law.

          9.16 WAIVER OF PUNITIVE AND OTHER DAMAGES AND JURY TRIAL.

          (a)  THE PARTIES TO THIS AGREEMENT EXPRESSLY WAIVE AND FOREGO ANY
     RIGHT TO RECOVER PUNITIVE, EXEMPLARY, LOST PROFITS, CONSEQUENTIAL OR
     SIMILAR DAMAGES IN ANY ARBITRATION, LAWSUIT, LITIGATION OR PROCEEDING
     ARISING OUT OF OR RESULTING FROM ANY CONTROVERSY OR CLAIM ARISING OUT OF OR
     RELATING TO THIS AGREEMENT, THE ADDITIONAL TRANSFER AGREEMENTS OR THE
     TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY.

          (b)  EACH PARTY ACKNOWLEDGES AND AGREES THAT ANY CONTROVERSY WHICH MAY
     ARISE UNDER THIS AGREEMENT OR ANY ADDITIONAL TRANSFER AGREEMENT IS LIKELY
     TO INVOLVE COMPLICATED AND DIFFICULT ISSUES, AND THEREFORE IT HEREBY
     IRREVOCABLY AND UNCONDITIONALLY WAIVES ANY RIGHT IT MAY HAVE TO A TRIAL BY
     JURY IN RESPECT OF ANY LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF OR
     RELATING TO THIS AGREEMENT, THE ADDITIONAL TRANSFER AGREEMENTS OR THE
     TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY.

                                                            Amended and Restated
                                       44               Stock Purchase Agreement
<Page>

          (c)  EACH PARTY CERTIFIES AND ACKNOWLEDGES THAT (i) NO REPRESENTATIVE,
     AGENT OR ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY OR
     OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF LITIGATION,
     SEEK TO ENFORCE EITHER OF THE FOREGOING WAIVERS, (ii) IT UNDERSTANDS AND
     HAS CONSIDERED THE IMPLICATIONS OF SUCH WAIVERS, (iii) IT MAKES SUCH
     WAIVERS VOLUNTARILY, AND (iv) IT HAS BEEN INDUCED TO ENTER INTO THIS
     AGREEMENT AND ANY ADDITIONAL TRANSFER AGREEMENT BY, AMONG OTHER THINGS, THE
     MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION 9.16.

          9.17 CERTAIN DEFINITIONS. The following terms used herein shall have
the following meanings:

          (a)  "AFFILIATE" means, with respect to any specified Person, a Person
     that directly, or indirectly through one or more intermediaries, controls,
     or is controlled by, or is under common control with, the Person specified;

          (b)  "ANCILLARY AGREEMENTS" means any and all agreements, other than
     this Agreement and the Additional Transfer Agreements, entered into among
     the Sellers and the Purchaser in connection with the transactions
     contemplated hereby.

          (c)  "APPLICABLE PERCENTAGE" means, (i) with respect to any Company
     listed on Exhibit B-1, the percentage amount listed opposite such Company's
     name on Exhibit B-1, and (ii) with respect to Thermometrics Beijing, 90%.

          (d)  "BOND" means any letter of credit, surety, performance, customs
     or excise bond obtained prior to the Closing Date by a Seller or a
     Non-Company Affiliate to support or facilitate business transactions by a
     member of a Company Group or a German Branch, and any security furnished by
     a Seller, a member of a Company Group or a Non-Company Affiliate in
     connection therewith.

          (e)  "BUSINESS" means, with respect to any Company Group, member of a
     Company Group or German Branch, the business or operations of such Company
     Group, member of a Company Group or German Branch, as currently conducted
     by such Company Group or member thereof or German Branch.

          (f)  "BUSINESS DAY" means a day other than a Saturday, Sunday or other
     day on which commercial banks in New York, New York are authorized or
     required by law to close.

          (g)  "COMPANY GROUP" means any Company and its Subsidiaries. "Company
     Groups" means the Companies and their Subsidiaries.

                                                            Amended and Restated
                                        45              Stock Purchase Agreement
<Page>

          (h)  "CONTROL" (including the correlative terms "controlling,"
     "controlled by" and "UNDER COMMON CONTROL WITH") means the possession,
     direct or indirect, of the power to direct or cause the direction of the
     management and policies of a Person, whether through the ownership of
     voting equity interest, by contract or otherwise.

          (i)  "DUTCH ASSET PURCHASE AGREEMENT" means the asset purchase
     agreement, in the form to be reasonably agreed upon by the Purchaser and
     the Sellers, entered into as of the Closing Date between Spirent GmbH and
     the Purchaser (or its designated Subsidiary), whereby Spirent GmbH sells,
     and the Purchaser (or such designated Subsidiary) purchases, certain of the
     German Assets on the terms and conditions specified therein.

          (j)  "ENVIRONMENTAL LAW" means any law, common law, statute, rule,
     regulation, directive or order relating to (i) the manufacture, transport,
     use, treatment, recycling, storage, disposal, release or threatened release
     of Hazardous Substances, or (ii) the protection of human health or the
     environment (including, without limitation, natural resources, air, and
     surface or subsurface land or waters).

          (k)  "GERMAN ASSET PURCHASE AGREEMENT" means the asset purchase
     agreement, substantially in the form of Exhibit F hereto, entered into as
     of the Closing Date between Spirent GmbH and the Purchaser (or its
     designated Subsidiary), whereby Spirent GmbH sells, and the Purchaser (or
     such designated Subsidiary) purchases, certain of the German Assets on the
     terms and conditions specified therein.

          (l)  "GERMAN BRANCH" means any of the divisions of Spirent GmbH known
     as Thermometrics Germany, GEI Germany and Protimeter Germany.

          (m)  "GERMAN LIABILITIES" means the liabilities assumed by the
     Purchaser (or its designated Subsidiary) pursuant to the German Asset
     Purchase Agreement.

          (n)  "GUARANTY" means any guaranty, keepwell agreement, comfort letter
     or similar undertaking issued prior to the Closing Date by a Seller or a
     Non-Company Affiliate to support or facilitate business transactions by a
     member of a Company Group or a German Branch, and any security furnished by
     a Seller or a Non-Company Affiliate in connection therewith.

          (o)  "HAZARDOUS SUBSTANCE" means any material or substance that is:
     (i) listed, classified or regulated as a "hazardous waste," "hazardous
     substance," "toxic substance," pollutant or contaminant pursuant to any
     applicable Environmental Law, (ii) that is toxic, explosive, corrosive,
     flammable, infectious,

                                                            Amended and Restated
                                       46               Stock Purchase Agreement
<Page>

     radioactive, carcinogenic, mutagenic or otherwise hazardous and is
     regulated by any governmental authority or (iii) any petroleum product or
     by-product, asbestos or polychlorinated biphenyls.

          (p)  "KNOWLEDGE" means, with respect to any Seller and any member of
     any Company Group, the actual knowledge of any of the individuals listed on
     Schedule 9.17(p)(i), opposite the name of such member, obtained in the
     normal course of their respective duties as officers of a Seller or a
     Company; and with respect to the Purchaser, the actual knowledge of any of
     the individuals listed on Schedule 9.17(p)(ii);

          (q)  "ORGANIZATIONAL DOCUMENTS" means any applicable certificates or
     articles of incorporation, association or limited partnership, memoranda of
     association, by-laws and other organizational documents, and any amendments
     or restatements thereto or thereof.

          (r)  "PERSON" means an individual, corporation, partnership,
     association, joint-stock company, trust, unincorporated organization or
     government or political subdivision thereof; and

          (s)  "SUBSIDIARY" means, with respect to any Person, a corporation or
     other Person in which the first Person owns or controls, directly or
     indirectly, capital stock or other equity interests representing more than
     50% of the outstanding voting stock or other equity interests.

          (t)  "THIRD PARTY ACCOUNTANTS" means an internationally recognized
     accounting firm selected by mutual agreement by Spirent plc and the
     Purchaser.

          (u)  "U. S. COMBINED INCOME TAXES," as such term is used in the Offer
     Statement, means U.S. federal income taxes and California state unitary
     income taxes.

                                                            Amended and Restated
                                       47               Stock Purchase Agreement
<Page>

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be executed as of the date first above written.


                                       SELLERS:

                                       SPIRENT PLC

                                       By
                                          ----------------------------
                                          Name:
                                          Title:

                                       SPIRENT B.V.

                                       By
                                          ----------------------------
                                          Name:
                                          Title:

                                       SPIRENT INTERNATIONAL INC.

                                       By
                                          ----------------------------
                                          Name:
                                          Title:

                                       SPIRENT GMBH

                                       By
                                          ----------------------------
                                          Name:
                                          Title:

                                                            Amended and Restated
                                                        Stock Purchase Agreement

<Page>

                                        PURCHASER:

                                        GENERAL ELECTRIC COMPANY

                                       By
                                          ----------------------------
                                          Name:
                                          Title:

                                                            Amended and Restated
                                                        Stock Purchase Agreement

<Page>

                               AMENDMENT NO. 1 TO
                  AMENDED AND RESTATED STOCK PURCHASE AGREEMENT

     This AMENDMENT NO. 1 TO AMENDED AND RESTATED STOCK PURCHASE AGREEMENT,
dated as of November 9, 2001, by and among Spirent plc, a company formed under
the laws of England and Wales, Spirent B.V., a Netherlands corporation, Spirent
International Inc., a Delaware corporation, and Spirent GmbH, a German
corporation (collectively, the "SELLERS"), and General Electric Company, a New
York corporation (the "PURCHASER"), amends the Amended and Restated Stock
Purchase Agreement, dated as of September 10, 2001 (the "PURCHASE AGREEMENT"),
by and among each of the Sellers and the Purchaser.

                               W I T N E S S E T H

          WHEREAS, the Sellers and the Purchaser desire to amend certain
provisions of the Purchase Agreement to be effective as of September 7, 2001;

     NOW, THEREFORE, for good and valuable consideration the receipt and
sufficiency of which is hereby acknowledged, the Sellers and the Purchaser do
hereby agree as follows:

     Section 1. AMENDMENTS.

     1.1. NOTIFICATIONS. Section 4.5 of the Purchase Agreement is hereby amended
to read in its entirety as follows:

          (a)   From the date hereof to the Closing Date, the Sellers shall
     promptly notify the Purchaser in writing of (i) any representation or
     warranty made by them contained in this Agreement or any Additional
     Transfer Agreement becoming untrue or inaccurate in any material respect or
     (ii) the failure by any Seller, any member of the Company Groups or the
     German Branches to comply with or satisfy in any material respect any
     covenant, condition or agreement to be complied with or satisfied by any of
     them under this Agreement or any Additional Transfer Agreement prior to the
     Closing.

          (b)   From the date hereof to the Closing Date, the Purchaser shall
     promptly notify the Sellers in writing of (i) any representation or
     warranty made by it contained in this Agreement or any Additional Transfer
     Agreement becoming untrue or inaccurate in any material respect or (ii) the
     failure by the Purchaser to comply with or satisfy in any material respect
     any covenant, condition or agreement to be complied with or satisfied by
     such party under this Agreement or any Additional Transfer Agreement prior
     to the Closing.

                                        1
<Page>

     1.2. INDEMNIFICATION BY THE SELLERS.

          (a)   Section 7.2.1(d) of the Purchase Agreement is hereby amended to
read in its entirety as follows:

          (d)   The Purchaser Indemnitees shall not be entitled to make a claim
          for indemnification under this Section 7 for any breach by any Seller
          of any covenant, representation or warranty set forth in this
          Agreement if the Purchaser had actual knowledge of such breach, or of
          the facts or circumstances giving rise to such breach, prior to the
          date of this Agreement. The Purchaser shall be entitled to make a
          claim for a breach of a covenant, representation or warranty set forth
          in this Agreement if the Purchaser first obtained knowledge of such
          breach, or of the facts or circumstances giving rise to such breach,
          after the date of this Agreement. The covenants, representations and
          warranties of the Sellers contained in this Agreement will not be
          deemed to be waived or otherwise modified or affected by any
          investigation made by the Purchaser on or following the date of this
          Agreement.

          (b)   Section 7.2.1 of the Purchase Agreement is hereby amended to add
the following text after subsection (e) of Section 7.2.1:

                (f)  In the event that the Purchaser believes that there is or
          may have been a breach of any of the representations set forth in
          Section 2.16 for which any Purchaser Indemnitee may seek
          indemnification hereunder ("ENVIRONMENTAL ISSUES"),

                     (i)   The Purchaser shall provide to the Sellers prompt
                notice of any Environmental Issues upon the determination by
                Purchaser that such Environmental Issues are reasonably likely
                to exist. The Purchaser and the Sellers will participate jointly
                in all communications, discussions and negotiations with any
                environmental regulatory authority with jurisdiction over the
                matter that is the subject of such Environmental Issue and with
                any landlord or other interested party concerning such matter,
                and neither the Purchaser nor any Seller may conduct any such
                communications, discussions or negotiations without the
                participation or prior written consent of the other party. The
                Purchaser and the Sellers shall provide each other with copies
                of all correspondence to or from any environmental regulatory
                authority, landlord or other interested party concerning
                investigation, monitoring or remediation activities relating to
                any Environmental Issue as well as copies of any and all
                remediation action plans, closure plans or similar plans.

                                        2
<Page>

                     (ii)  The Sellers and their consultants shall be permitted
                to discuss with the Purchaser and its environmental consultants
                (and the Purchaser shall provide the Sellers access to the
                Purchaser's environmental consultants with respect to) matters
                relating to any Environmental Issues so as to become informed
                concerning all maters related to such Environmental Issues and
                all procedures, methods, tests and approaches to be utilized in
                connection therewith. The Purchaser shall promptly provide to
                the Sellers copies of all reports prepared by Purchaser's
                environmental consultants regarding Environmental Issues.

                     (iii) Any investigation, monitoring and remediation of any
                environmental condition relating to an Environmental Issue shall
                be controlled by the Purchaser, PROVIDED that the Purchaser
                shall be solely responsible for the consequences of such
                activities. The Purchaser shall consult with and keep the
                Sellers informed regarding such investigation, monitoring and
                remediation activities. The Sellers shall be granted reasonable
                access to the site of any such environmental condition during
                normal business hours or at such other times as may be agreed
                upon by the Purchaser and the Sellers.

                     (iv)  If the Purchaser and the Sellers do not agree with
                respect to any proposed communications, discussions or
                negotiations with any environmental regulatory authority,
                landlord or other interested party, or with respect to any
                proposed investigation, monitoring or remediation of any
                environmental condition, the Purchaser will make the final
                decision and will retain ultimate control regarding any such
                communications, discussions, negotiations, investigation,
                monitoring and remediation, PROVIDED THAT, where the Purchaser
                pursues a course of action with which the Seller does not agree,
                any indemnity to which the Purchaser Indemnitees may be entitled
                under this Section 7.2.1 in respect of such environmental
                condition shall not cover any portion of the Purchaser
                Indemnitees' Damages that exceed the Damages that the Purchaser
                Indemnitees would have incurred or sustained had they had
                followed a commercially reasonable course of action required to
                comply with applicable law.

     1.3. INDEMNIFICATION BY THE PURCHASER. Section 7.2.2(d) of the Purchase
Agreement is hereby amended to read in its entirety as follows:

          (d)   The Seller Indemnitees shall not be entitled to make a claim for
     indemnification under this Section 7 for any breach by the Purchaser of any
     covenant, representation or warranty set forth in this Agreement if the
     Sellers had actual knowledge of such breach, or of the facts or
     circumstances giving rise to

                                        3
<Page>

     such breach, prior to the date of this Agreement. The Sellers shall be
     entitled to make a claim for a breach of a covenant, representation or
     warranty set forth in this Agreement if the Sellers first obtained
     knowledge of such breach, or of the facts or circumstances giving rise to
     such breach, after the date of this Agreement. The covenants,
     representations and warranties of the Purchaser contained in this Agreement
     will not be deemed to be waived or otherwise modified or affected by any
     investigation made by the Sellers on or following the date of this
     Agreement.

     Section 2. MISCELLANEOUS

     2.1. COUNTERPARTS. This Amendment may be executed in counterparts, each of
which together shall constitute one and the same instrument.

     2.2. RATIFICATION AND CONFIRMATION. Except as expressly amended hereby, the
terms of the Purchase Agreement are hereby ratified and confirmed and shall
remain in full force and effect.

     2.3. GOVERNING LAW. This Amendment shall be construed, performed and
enforced in accordance with the laws of the State of New York, without regard to
the conflicts of law principles of such state.

                                        4
<Page>

     IN WITNESS WHEREOF, the parties have duly executed this Amendment No. 1 to
Amended and Restated Stock Purchase Agreement as of the date first above
written.

                                       SELLERS:

                                       SPIRENT PLC

                                       By
                                          ------------------------------
                                          Name:
                                          Title:

                                       SPIRENT B.V.

                                       By
                                          ------------------------------
                                          Name:
                                          Title:

                                       SPIRENT INTERNATIONAL INC.

                                       By
                                          ------------------------------
                                          Name:
                                          Title:

                                       SPIRENT GMBH

                                       By
                                          ------------------------------
                                          Name:
                                          Title:

                                       PURCHASER:

                                       GENERAL ELECTRIC COMPANY

                                       By
                                          ------------------------------
                                          Name:
                                          Title:

                                        5