Document:

<PAGE>

                                                                    EXHIBIT 4.62

CLIFFORD                                                          CONFORMED COPY
CHANCE
PUNDER

                     MARCONI COMMUNICATIONS REAL ESTATE GMBH

                                   AS ASSIGNOR

                                       AND

                   THE LAW DEBENTURE TRUST CORPORATION p.l.c.

                               AS SECURITY TRUSTEE

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                      SHAREHOLDER LOAN ASSIGNMENT AGREEMENT

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<PAGE>

                                    CONTENTS
<TABLE>
<CAPTION>
CLAUSE                                                                                                  PAGE
<S>                                                                                                     <C>
1.       Definitions and Languages.....................................................................   2

2.       Secured Obligations...........................................................................   3

3.       Assignment....................................................................................   3

4.       Information...................................................................................   3

5.       Transfer of Ancillary Rights..................................................................   4

6.       Collection of Receivables by the Assignor.....................................................   4

7.       Right to Realisation upon Enforcement Event...................................................   5

8.       Limitation of Security........................................................................   5

9.       Further Assurance.............................................................................   7

10.      Release (Sicherheitenfreigabe)................................................................   7

11.      Bookkeeping and Data-Processing...............................................................   8

12.      Expenses, Costs and Taxes.....................................................................   9

13.      Partial Invalidity, Waiver...................................................................   10

14.      Amendments; Waiver...........................................................................   10

15.      Notices and their Language...................................................................   10

16.      Applicable Law, Jurisdiction.................................................................   12

18.      Effectiveness................................................................................   13

19.      Counterparts.................................................................................   13
</TABLE>

<PAGE>

THIS AGREEMENT is made the 16th day of May 2003

BETWEEN:

1.       Marconi Communications Real Estate GmbH, a limited liability company
         organised under the laws of the Federal Republic of Germany, having its
         business address at GerberstraBe 33, D-71522 Backnang, which is
         registered in the commercial register (Handelsregister) of the local
         court (Amtsgericht) of Backnang under HRB 1561 (the "ASSIGNOR"); and

2.       The Law Debenture Trust Corporation p.l.c., having its business address
         at Fifth Floor, 100 Wood Street, London, EC2V 7EX, England in its
         capacity as security trustee under the Relevant Documents (the
         "SECURITY TRUSTEE").

WHEREAS:

(A)      Marconi Corporation p.l.c. (the "ISSUER") has agreed to issue the
         following notes:

         (i)      USD equivalent of GBP 450,000,000 senior secured notes due
                  2008;

         (ii)     USD 300,000,000 plus USD equivalent of GBP 117,270,000 of
                  junior secured notes due 2008;

                  the notes under (i) being documented in a senior note
                  indenture dated on or about 19 May 2003 between, inter alios,
                  the Issuer and Law Debenture Trust Company of New York as
                  Senior Note Trustee and the notes under (ii) being documented
                  in a junior note indenture dated on or about 19 May 2003
                  between, inter alios, the Issuer and JPMorgan Chase Bank as
                  Junior Note Trustee (together the "INDENTURES").

(B)      The security created by or pursuant to this Agreement is to be granted
         to and administered by the Security Trustee for itself and as trustee
         of the Secured Creditors pursuant to the relevant provisions of a
         security trust and intercreditor deed dated on or about 19 May 2003
         between, inter alios, the Issuer, Law Debenture Trust Company of New
         York as Senior Note Trustee, JPMorgan Chase Bank as Junior Note
         Trustee, the Security Trustee and the Obligors (as defined therein
         including the Assignor) as amended from time to time (the "SECURITY
         TRUST AND INTERCREDITOR DEED").

(C)      The Assignor has agreed to assign the Receivables (as defined below) as
         security for the payment and discharge of the Secured Obligations (as
         defined below) subject to the terms and conditions set out herein.

                                     - 1 -

<PAGE>

NOW, IT IS AGREED as follows:

1.       DEFINITIONS AND LANGUAGES

1.1      In this Agreement:

         "AUTHORIZATION" has the meaning given to it in Clause 6.

         "CONTINUING" in relation to an Enforcement Event, shall be construed as
         a reference to an acceleration of any Secured Obligation (other than
         Secured Obligations arising under the New Bonding Facility Agreement)
         where such acceleration has not been rescinded in writing or a
         declaration that the Secured Obligations (other than Secured
         Obligations arising under the New Bonding Facility Agreement) are
         prematurely due and payable (other than solely as a result of it
         becoming unlawful for a Secured Creditor to perform its obligations
         under the Relevant Documents) where such declaration has not been
         revoked in writing or any failure by an Obligor to pay any principal
         amount in respect of any Secured Obligations (other than Secured
         Obligations arising under the New Bonding Facility Agreement) whether
         on maturity or otherwise which has not been waived in writing. For the
         purposes of this definition of "continuing" the expression "Secured
         Obligations" shall have the same meaning as in the Security Trust and
         Intercreditor Deed.

         "RECEIVABLES" means all present and future rights and claims owing to
         the Assignor and originating from shareholders loans, including but not
         limited to those specified in Schedule 1.

         "SECURED OBLIGATIONS" has the meaning given to it under clause 2.

         "SECURITY TRUST AND INTERCREDITOR DEED" has the meaning given to it in
         Clause (B) of the recitals.

1.2      Unless otherwise defined herein or unless the context requires,
         capitalised terms shall have the same meaning as ascribed thereto in
         the Security Trust and Intercreditor Deed.

1.3      This Agreement is made in the English language. For the avoidance of
         doubt, the English language version of this Agreement shall prevail
         over any translation of this Agreement. However, where a German
         translation of a word or phrase appears in the text of this Agreement,
         the German translation of such word or phrase shall prevail.

                                     - 2 -

<PAGE>

1.4      The parties hereto each acknowledge that the Security Trustee, when
         acting hereunder, shall, to the extent permitted under the laws of
         Germany, be acting in accordance with and subject to the terms of the
         Security Trust and Intercreditor Deed.

2.       SECURED OBLIGATIONS

         The assignment hereunder (the "ASSIGNMENT") is constituted in order to
         secure together with other security granted by the Assignor the prompt
         and complete satisfaction of any and all obligations (present and
         future, actual and contingent) which are (or are expressed to be) or
         become owing by the Assignor to the Secured Creditors or any of them
         (including any future assignee or transferee of any of the Secured
         Creditors by way of transfer or assignment (including by way of
         assumption of debt (Vertragsubernahme)) under the Relevant Documents
         (including, but not limited to the parallel obligations of the Assignor
         pursuant to clause 3 of the Security Trust and Intercreditor Deed to
         pay to the Security Trustee sums equal to the sums owed by the Assignor
         to the Secured Creditors or any of them) (the "SECURED Obligations") up
         to an aggregate amount of EUR 30 million.

3.       ASSIGNMENT

3.1      The Assignor hereby assigns the Receivables to the Security Trustee in
         its capacity as Security Trustee for the benefit of the Secured
         Creditors.

3.2      The Security Trustee hereby accepts the assignment of the Receivables.

3.3      Subject to clause 3.4 below the existing Receivables shall pass over to
         the Security Trustee on execution of this Agreement, and any future
         Receivables shall pass over to the Security Trustee at the date such
         Receivables arise.

3.4      Notwithstanding the other provisions in this Clause 3 the assignment of
         all Receivables shall be effective only if and upon the condition
         (aufschiebende Bedingung) that the aggregate amount of Receivables owed
         to the Assignor exceeds GBP 20 million or its equivalent in any other
         currency.

4.       INFORMATION

4.1      The Assignor shall, upon request of the Security Trustee deliver to the
         Security Trustee such further information on the Receivables as deemed
         necessary by the Security Trustee.

                                     - 3 -

<PAGE>

4.2      The Assignor undertakes to provide the Security Trustee promptly at its
         request with all information and documents which are necessary for
         perfecting and/or enforcing the security created hereby.

5.       TRANSFER OF ANCILLARY RIGHTS

5.1      Together with all the Receivables assigned and transferred in
         accordance with this Agreement, all securities, collateral and all
         ancillary rights pertaining thereto, as well as all rights resulting
         from the underlying agreements (hereinafter together with the
         Receivables referred to as the "COLLATERAL"), are hereby transferred to
         and assigned to the Security Trustee, to the extent such rights are not
         automatically transferred to the Security Trustee pursuant to Section
         401 of the German Civil Code (Burgerliches Gesetzbuch). The Assignor's
         claims to demand repossession against the direct possessor are assigned
         to the Security Trustee at the same time.

5.2      If the Assignor is in direct possession of the Collateral, the delivery
         of such Collateral shall be substituted by the Assignor holding the
         Collateral in gratuitous custody for the Security Trustee.

6.       COLLECTION OF RECEIVABLES BY THE ASSIGNOR

         The Security Trustee authorises the Assignor to collect the Receivables
         (such authorization hereinafter referred to as the "AUTHORIZATION") to
         the extent not expressly prohibited by the terms of the Indentures. The
         Security Trustee may revoke the Authorization upon the occurrence of an
         Insolvency Event of Default and the Security Trustee shall revoke the
         Authorization if the Security Trustee has been so instructed pursuant
         to the Security Trust and Intercreditor Deed upon or at any time after
         the occurrence of an Event of Default which is continuing, whereupon
         the Assignor may continue to collect the Receivables but shall promptly
         surrender the proceeds to the Security Trustee. Until the requirements
         set out in Clause 7.1 are met the Security Trustee shall treat such
         proceeds as additional collateral for the Secured Obligations. To the
         extent that the Authorization is revoked, the Security Trustee may
         request that copies of all documents relating to the Receivables be
         handed over to it and the Assignor hereby agrees to comply with any
         such request. For the avoidance of doubt nothing in this Clause 6 shall
         restrict the right of the Security Trustee to enforce its rights under
         Clause 7 if the requirements set out in Clause 7.1 are met.

                                     - 4 -

<PAGE>

7.       RIGHT TO REALISATION UPON ENFORCEMENT EVENT

7.1      At any time after the occurrence of an Enforcement Event which is
         continuing and the Security Trustee (acting on instructions received
         pursuant to the terms of the Security Trust and Intercreditor Deed)
         giving notice to the Issuer thereof and if any of the Secured
         Obligations became due and payable the Security Trustee shall, in its
         discretion, be entitled to arrange for the collection or disposal of
         Receivables for and on behalf of the Secured Creditors in accordance
         with the provisions of this Clause 7.

7.2      To the extent that the Authorization is revoked, the Security Trustee
         may request that originals of all documents relating to the Receivables
         be handed over to it and the Assignor hereby agrees to comply with any
         such request.

7.3      The Security Trustee shall realise all or part of the Collateral to the
         extent necessary to satisfy any outstanding Secured Obligations by
         collecting all or part of the Receivables, it being understood that the
         Security Trustee shall apply the proceeds of such realisation towards
         the Secured Obligations in accordance with and subject to the terms of
         the Security Trust and Intercreditor Deed.

7.4      The Security Trustee may request the Assignor to collect the
         Receivables for and on behalf of the Secured Creditors and the Assignor
         shall promptly comply with such request.

7.5      If the Security Trustee collects any Receivables pursuant to this
         Clause 7, it may take all measures and enter into all agreements with
         the debtors of the Receivables which it considers to be expedient.

7.6      With respect to the realisation of the Collateral, the Security Trustee
         will take into consideration the legitimate interest of the Assignor.

8.       LIMITATION OF SECURITY

8.1      The right to enforce the security interests created hereunder shall, to
         the extent that the Secured Obligations represent those of an
         affiliated company (verbundenes Unternehmen) within the meaning of
         Section 15 et seq. of the German Stock Corporation Act (Aktiengesetz)
         of the Assignor (other than any of the Assignor's subsidiaries), at all
         times be limited to an amount equal to the Assignor's assets (the
         calculation of which shall take into account the captions reflected in
         Section 266 sub-section (2) A, B and C of the German Commercial Code
         (Handelsgesetzbuch)) less the sum of (A) the Assignor's liabilities
         (the calculation of which shall take into account the captions
         reflected in Section 266 subsection (3) B, C and D of the

                                     - 5 -

<PAGE>

         count the captions reflected in Section 266 subsection (3)B, C and D of
         the German Commercial Code), and (B) the stated share capital
         (Stammkapital) of the Assignor (the "NET ASSETS").

8.2      The Assignor shall realise, to the extent legally permitted and, in
         respect of the Assignor, commercially justifiable, in a situation where
         the Assignor does not have sufficient Net Assets to maintain its
         registered share capital, any and all of its assets that are shown in
         the balance sheet with a book value (Buchwert) that is significantly
         lower than the market value of the assets if the asset is not necessary
         for the Assignor's business (betriebsnotwendig).

8.3      The Security Trustee shall enforce any security interest created
         hereunder against the Assignor in accordance with the following
         procedure:

                  (i)      The Assignor shall, following a notification by the
                           Security Trustee to the Assignor that an Enforcement
                           Event has occurred and that the Security Trustee
                           intends to enforce the security interests created
                           hereunder, deliver to the Security Trustee within
                           sixty days of such notification an auditors'
                           determination from a firm of auditors of
                           international standard and reputation (the "AUDITORS'
                           DETERMINATION") stating the value of the Net Assets,
                           i.e., the amounts which may be claimed against the
                           Assignor under the security interests created
                           hereunder having regard to Sections 30 and 31 of the
                           German Limited Liability Companies Act.

                  (ii)     The Auditors' Determination, i.e., the amount which
                           may be claimed against the Assignor under the
                           security interests created hereunder, having regard
                           to Section 30 and 31 of the German Limited Liability
                           Companies Act, shall take into account the generally
                           accepted accounting principles applicable from time
                           to time in Germany (GAAP) and be based on the same
                           principles that were applied when establishing the
                           previous year's balance sheet.

                  (iii)    The amount specified in the relevant Auditors'
                           Determination pertaining to the Assignor shall be
                           up-to-date and in any event such Auditors'
                           Determination shall have been prepared as of a date
                           no earlier than 15 business days prior to the date of
                           notification by the Security Trustee to the Assignor
                           that it intends to enforce the security interests
                           created hereunder.

                                     - 6 -

<PAGE>

                  (iv)     If the Assignor fails to deliver the Auditors'
                           Determination to the Security Trustee within the
                           sixty day period stated in (i) above, the Security
                           Trustee shall be entitled to enforce the security
                           interests created hereunder against the Assignor
                           without limitation.

9.       FURTHER ASSURANCE

         Insofar as additional documents, declarations or actions (including
         making all filings and registrations) are necessary for the creation,
         perfection, protection or maintenance of the security interests created
         (or purported to be created) hereunder (or any of them) in favour of
         the Security Trustee or for the exercise of all rights, powers and
         remedies of the Security Trustee provided by or pursuant to this
         Agreement or by law or to facilitate the realisation of the security
         interests created (or purported to be created) hereunder (or any of
         them), the Assignor shall at the Security Trustee's request enter into
         or provide such documents, make such declarations and/or undertake such
         actions at the Assignor's cost and expense.

10.      RELEASE (SICHERHEITENFREIGABE)

10.1     Upon complete and irrevocable satisfaction of the Secured Obligations,
         the Security Trustee shall (in accordance with the terms and subject to
         the conditions and circumstances set out in the Security Trust and
         Intercreditor Deed and without recourse to, or any representations or
         warranty by, the Security Trustee or any of its nominees) at the cost
         and expense of the Assignor reassign and/or transfer, as the case may
         require, to the Assignor, which shall accept such re-assignment and/or
         re-transfer, the Collateral and surrender the excess proceeds, if any,
         resulting from any realisation thereof. The Security Trustee will,
         however, transfer any Receivables to a third person if so required by
         law.

10.2     At any time when the total value of the aggregate security granted by
         the Assignor to secure the Secured Obligations (the "SECURITY") which
         can be expected to be realised in the event of an enforcement of the
         Security (realisierbarer Wert) exceeds 110% of the Secured Obligations
         (the "LIMIT") not only temporarily, the Security Trustee shall (in
         accordance with the terms and subject to the conditions and
         circumstances set out in the Security Trust and Intercreditor Deed and
         without recourse to, or any representations or warranty by, the
         Security Trustee or any of its nominees) on demand of the Assignor
         release such part of the Security (Sicherheitenfreigabe) as the
         Security Trustee may in its discretion determine so as to reduce the
         realisable value of the Security to the Limit.

                                     - 7 -

<PAGE>

11.      BOOKKEEPING AND DATA-PROCESSING

11.1     If proof or documents which are necessary to identify the Collateral
         have been handed over by the Assignor to a third party (in particular a
         bookkeeping firm or a tax consultant) the Assignor hereby transfers (on
         condition of (aufschiebende Bedingung) (i) the occurrence of an
         Insolvency Event of Default or (ii) notice by the Security Trustee if
         the Security Trustee has been so instructed pursuant to the Security
         Trust and Intercreditor Deed upon or at any time after the occurrence
         of an Event of Default which is continuing)to the Security Trustee, who
         accepts such transfer, its right to demand from such third party the
         return of the information and documents. The Assignor hereby undertakes
         to instruct the third party upon such transfer to provide the Security
         Trustee upon its demand with such information and documents which are
         necessary to perfect and/or enforce the security created hereby.

11.2     If details concerning the Collateral or any part thereof have been
         stored in an electronic data-processing system, then, upon the
         occurrence of an Insolvency Event of Default or upon request by the
         Security Trustee if the Security Trustee has been so instructed
         pursuant to the Security Trust and Intercreditor Deed upon or at any
         time after the occurrence of an Event of Default which is continuing,
         the Assignor shall allow the Security Trustee access to the computer,
         including the peripheral equipment and all data concerning the
         Collateral or such part thereof. Moreover, software operators shall be
         made available insofar as so required, and any assistance required
         shall be provided to the Security Trustee. If a third party handles the
         electronic processing of data, the Assignor hereby transfers (on
         condition of (aufschiebende Bedingung) (i) the occurrence of an
         Insolvency Event of Default or (ii) notice by the Security Trustee if
         the Security Trustee has been so instructed pursuant to the Security
         Trust and Intercreditor Deed upon or at any time after the occurrence
         of an Event of Default which is continuing) to the Security Trustee,
         who accepts this transfer, all rights against such third party relating
         to these services. The Assignor hereby undertakes to instruct the third
         party upon such transfer to handle the processing of data for the
         Security Trustee upon its demand as it did for the Assignor.

11.3     After transfer of the rights to the Security Trustee as contemplated in
         Clauses 11.1 and 11.2, the Security Trustee shall promptly upon request
         of the Assignor or after the Security Trustee receiving instructions
         pursuant to the Security Trust and Intercreditor Deed instruct the
         third party to provide the Assignor with such services and information
         as necessary for the Assignor in connection with the preparation and
         delivery of the Auditors' Determination.

                                     - 8 -

<PAGE>

12.      EXPENSES, COSTS AND TAXES

12.1     EXPENSES

         The Assignor shall, from time to time and promptly on demand by the
         Security Trustee reimburse to the Security Trustee all costs and
         expenses (including legal fees) on a full indemnity basis together with
         any applicable VAT incurred by the Security Trustee and any Delegate
         (provided that in relation to sub-clause (i) of this Clause 12, such
         costs and expenses must be properly incurred) in connection with:

                  (i)      the execution, release and discharge of this
                           Agreement and the security created or intended to be
                           created in respect of the Collateral and the
                           perfection of the security contemplated in this
                           Agreement or in any such documents or forming part of
                           the security created or intended to be created in
                           respect of the Collateral;

                  (ii)     the actual or contemplated exercise, preservation
                           and/or enforcement of any of the rights, powers and
                           remedies of, or the performance of the duties and
                           obligations of, the Security Trustee or any Delegate,
                           or any amendment or waiver in respect of this
                           Agreement;

                  (iii)    the foreclosure of any Collateral; and

                  (iv)     the preservation and/or enforcement of the security
                           created or intended to be created in respect of the
                           Collateral,

                  which shall carry interest (before and after any judgment and
                  to the extent interest at a default rate is not otherwise
                  being paid on such sum) from the date of such demand until so
                  reimbursed calculated on a daily basis at the rate determined
                  in accordance with the provisions of clause 18.4 (Interest on
                  Demands) of the Security Trust and Intercreditor Deed.

12.2     TAXES

         The Assignor shall pay, promptly on demand of the Security Trustee all
         stamp, registration, notarial and other similar Taxes or fees paid or
         payable by the Security Trustee in connection with any action taken or
         contemplated by or on behalf of the Security Trustee for perfecting,
         enforcing, releasing, cancelling, reassigning or resolving any doubt
         concerning, or for any other purpose in relation to this Agreement, any
         amendment thereto, any transfer and/or assignment of the rights and/or
         obligations under the same or the security created or intended to be
         created in respect of the Collateral and shall, from time to time,
         indemnify the Security Trustee

                                     - 9 -

<PAGE>

         promptly on demand against any liabilities, costs, claims and expenses
         resulting from any failure to pay by the Assignor or any delay by the
         Assignor in paying any such Taxes or fees.

13.      PARTIAL INVALIDITY, WAIVER

13.1     If at any time, any one or more of the provisions hereof is or becomes
         invalid, illegal or unenforceable in any respect under the law of any
         jurisdiction, that provision shall as to that jurisdiction be
         ineffective to the extent necessary without affecting or impairing the
         validity, legality and enforceability of the remaining provisions of
         this Agreement or of such provisions in any other jurisdiction. The
         invalid or unenforceable provision shall be deemed replaced by a valid,
         legal and enforceable provision which comes as close as possible to the
         orginal intent of the parties as to the invalid, illegal or
         unenforceable provision. This shall apply analogously in the case of
         gaps.

13.2     No failure to exercise, nor any delay in exercising, on the part of the
         Security Trustee, any right or remedy hereunder shall operate as a
         waiver thereof, nor shall any single or partial exercise of any right
         or remedy prevent any further or other exercise thereof or the exercise
         of any other right or remedy. The rights and remedies provided
         hereunder are cumulative and not exclusive of any rights or remedies
         provided by law.

14.      AMENDMENTS; WAIVER

         This Agreement may be amended, modified or waived only in writing in an
         agreement signed by the Security Trustee. This also applies to this
         Clause 14.

15.      NOTICES AND THEIR LANGUAGE

15.1     Each communication under or in connection with this Agreement shall be
         made in writing and, unless otherwise stated, may be made by fax or
         letter.

15.2     Any communication or document to be made or delivered under or in
         connection with this Agreement shall be made or delivered to the
         following addresses or fax numbers (and for the attention of the
         department or officer noted):

                                     - 10 -

<PAGE>

         for the Assignor:               Marconi Communications Real Estate GmbH
                                         Address:   GerberstraBe 33
                                                    D-71522 Backnang

                                         Fax: 07191 13 2419
                                         Attention: Hans-Werner Altermann
                                                    Legal Advisor

         for the Security Trustee: The Law Debenture Trust Corporation p.l.c.

                                         Address:   Fifth Floor
                                                    100 Wood Street
                                                    London EC2V 7EX
                                                    England

                                         Fax:       +44 20 7696 5261
                                         Attention: Manager Trust Adminstration

         or to such other address as the recipient may notify or may have
         notified to the other party in writing.

15.3     DELIVERY

15.3.1   Any communication or document made or delivered by one person to
         another under or in connection with this Agreement will only be
         effective:

         (a)      if by way of fax, when received in legible form; or

         (b)      if by way of letter, when it has been left at the address
                  specified in Clause 15.2 above or five Business Days after
                  being deposited in the post postage prepaid in an envelope
                  addressed to the addressee at that address,

         and, if a particular department or officer is specified as part of that
         address, if addressed to that department or officer.

15.3.2   Notwithstanding the provisions of sub-clause 15.3.1 (b) above, any
         communication or document to be made or delivered to the Security
         Trustee will be effective only when actually received by the Security
         Trustee and then only if it is expressly marked for the attention of
         the department or officer identified in Clause 15.2 (or any substitute
         department or officer as such person shall specify for this purpose).

                                     - 11 -

<PAGE>

15.4     Any notice given under or connection with this Agreement shall be in
         the English language. All other documents provided under or in
         connection with this Agreement shall be in the English language or, if
         in any other language, accompanied by a translation into English which
         if reasonably requested by the Security Trustee shall be a certified
         translation. In the event of any conflict between the English text and
         the text in any other language, the English text shall prevail unless
         the document is a contractual, statutory or other official document.

16.      APPLICABLE LAW, JURISDICTION

16.1     APPLICABLE LAW

         This Agreement shall be governed by and construed in accordance with
         the laws of the Federal Republic of Germany.

16.2     GERMAN COURTS

         The courts of Frankfurt am Main have exclusive jurisdiction to settle
         any dispute (a "DISPUTE") arising out of or in connection with this
         Agreement (including a dispute regarding the existence, validity or
         termination of this Agreement or the consequences of its nullity).

16.3     CONVENIENT FORUM

         The parties agree that the courts of Frankfurt am Main are the most
         appropriate and convenient courts to settle Disputes between them and,
         accordingly, that they will not argue to the contrary.

16.4     NON-EXCLUSIVE JURISDICTION

         This Clause 16 is for the benefit of the Secured Creditors only. As a
         result it does not prevent any Secured Creditor from taking proceedings
         relating to a Dispute ("PROCEEDINGS") in any other courts with
         jurisdiction. To the extent allowed by law, the Secured Creditors may
         take concurrent Proceedings in any number of jurisdictions.

17.      ASSIGNMENT

         The Security Trustee may assign and transfer all or any of its rights
         and obligations under this Agreement in accordance with the Security
         Trust and Intercreditor Deed. To the extent legally permissible the
         Security Trustee shall be entitled to disclose such information
         concerning the Assignor and this Agreement as the Security Trustee
         considers appropriate to any actual or proposed direct or indirect
         successor or to

                                     - 12 -

<PAGE>

         any person to whom information may be required to be disclosed by any
         applicable law.

18.      EFFECTIVENESS

         This Agreement shall become effective only subject to the condition
         precedent and at the time of the first original issuance of the Senior
         Notes.

19.      COUNTERPARTS

         This Agreement may be executed in any number of counterparts and by
         different parties hereto on separate counterparts each of which, when
         executed and delivered, shall constitute an original, but all the
         counterparts shall together constitute but one and the same instrument.

                                     - 13 -

<PAGE>

                                   SCHEDULE 1

                                SHAREHOLDER LOANS

                                     - 14 -

<PAGE>

                                 SIGNATURE PAGES

THIS SHAREHOLDER LOAN ASSIGNMENT AGREEMENT HAS BEEN ENTERED INTO ON THE DATE
STATED AT THE BEGINNING BY:

MARCONI COMMUNICATIONS REAL ESTATE GmbH

By: MARY SKELLY
    Name:  Mary Skelly
    Title: Attorney

THE LAW DEBENTURE TRUST CORPORATION p.l.c.

By: R. D. RANCE
    Name:  R. D. Rance
    Title: Director

                                     - 15 -<PAGE>
                                                                    EXHIBIT 4.63

                                                                  CONFORMED COPY

                                DATED 19 MAY 2003

                           Security Interest Agreement

                                   Over Shares

                  (1)   FS FINANCE CORP

                  (2)   THE LAW DEBENTURE TRUST CORPORATION P.L.C. AS SECURITY
                        TRUSTEE

                             COLLAS DAY         Advocates

                  P.O. Box 140, Manor Place,    Tel:  + 44 (0) 1481 723191
             St Peter Port, Guernsey GY1 4EW    Fax: + 44 (0) 1481 711880
                           www.collasday.com    E-Mail: inbox@collasday.com

                                   (Ref SC/jy)
<PAGE>
                                    CONTENTS
<TABLE>
<CAPTION>

CLAUSES                                                                                                     PAGE

<S>                                                                                                          <C>
1.       Definitions and Interpretation..............................................................        2

2.       Intercreditor Agreement.....................................................................        4

3.       Creation of Security Interest in the Securities.............................................        4

4.       Dividends and Voting Rights.................................................................        5

5.       Continuing Security.........................................................................        5

6.       Representations, Warranties and Undertakings by the Debtor..................................        6

7.       Powers of the Trustee upon Enforcement......................................................        6

8.       Restrictions on Charging and Disposal.......................................................        7

9.       Power of Attorney...........................................................................        7

10.      Preservation of other Security and Rights and Further Assurance.............................        7

11.      Notices.....................................................................................        8

12.      Expenses, Costs & Taxes.....................................................................        8

13.      General.....................................................................................        9

14.      Governing Law and Jurisdiction..............................................................        9

</TABLE>

Schedule - The Company and the Securities
<PAGE>
THIS AGREEMENT is dated     19 day of May 2003

BETWEEN

(1)   FS FINANCE CORP c/o Marconi Communications Inc., 333 Pierce Road - Suite
      370, Itasca, IL 60143 United States of America (the "DEBTOR"); and

(2)   THE LAW DEBENTURE TRUST CORPORATION P.L.C. (the "TRUSTEE") acting as
      Security Trustee, as trustee for itself and for the benefit of the other
      Secured Creditors (as defined below).

OPERATIVE PROVISIONS

1.    DEFINITIONS AND INTERPRETATION

1.1   In this Agreement unless the context otherwise requires, the following
      words and expressions shall have the following meanings:-

      ADDRESS FOR SERVICE           1 Le Marchant Street, St Peter Port,
                                    Guernsey

      COMPANY                       the company whose details are set out in
                                    Part 1 of the Schedule

      CONTINUING                    in relation to an Enforcement Event, an
                                    acceleration of any Obligation (other than
                                    Obligations arising under the New Bonding
                                    Facility Agreement) where such acceleration
                                    has not been rescinded in writing or a
                                    declaration that the Obligations (other than
                                    Obligations arising under the New Bonding
                                    Facility Agreement) are prematurely due and
                                    payable (other than solely as a result of it
                                    becoming unlawful for a Secured Creditor to
                                    perform its obligations under the Relevant
                                    Documents) where such declaration has not
                                    been revoked in writing or any failure by an
                                    Obligor to pay any principal amount in
                                    respect of any Obligations (other than
                                    Obligations arising under the New Bonding
                                    Facility Agreement) whether on maturity or
                                    otherwise which has not been remedied or
                                    waived in writing

      ENFORCEMENT EVENT             the acceleration of any Obligations or any
                                    declaration that any Obligations are
                                    prematurely due and payable (other than
                                    solely as a result of it becoming unlawful
                                    for a Secured Creditor to perform its
                                    obligations under the Relevant Documents) or
                                    any failure by any Obligor to pay any
                                    principal amount in respect of any
                                    Obligations whether on maturity or otherwise

      INTERCREDITOR AGREEMENT       the security trust and intercreditor
                                    agreement dated on or about the Issue Date
                                    between, among others, Marconi Corporation
                                    plc as Issuer and the Trustee as Security
                                    Trustee

                                                                               2
<PAGE>
         ISSUE DATE                 the date on which the Notes are issued

         LAW                        the Security Interests (Guernsey) Law, 1993

         OBLIGATIONS                has the meaning given to the term "Secured
                                    Obligations" in the Intercreditor Agreement

         REQUIRED CURRENCY          the currency or currencies in which the
                                    Secured Obligations are expressed from time
                                    to time

         SECURED CREDITORS          the Trustee, any Receiver or Delegate, the
                                    Depositary, the Paying Agent, the Registrar,
                                    the Senior Note Trustee (for itself and as
                                    trustee for the holders of the Senior
                                    Notes), the Junior Note Trustee (for itself
                                    and as trustee for the holders of the Junior
                                    Notes), the Escrow Bank, the New Bonding
                                    Facility Agent and each of the New Bonding
                                    Facility Banks and their successors and
                                    assigns

         SECURED OBLIGATIONS        all present and future indebtedness,
                                    liabilities and obligations (for the
                                    avoidance of doubt, including any
                                    liabilities and obligations which have been
                                    cash-collateralised by the Obligors) at any
                                    time of the Debtor under the Relevant
                                    Documents, both actual and contingent
                                    whether incurred solely or jointly or in any
                                    other capacity together with any of the
                                    following matters relating to or arising in
                                    respect of those liabilities and
                                    obligations:

                                    (a) any refinancing, novation, deferral
                                        or extension;

                                    (b) any obligation relating to any
                                        increase in the amount of such
                                        obligations;

                                    (c) any claim for damages or restitution;
                                        and

                                    (d) any claim as a result of any recovery
                                        by an Obligor of a payment or discharge,
                                        or non-allowability, on the grounds of
                                        preference,

                                    and any amounts that would be included in
                                    any of the above but for any discharge,
                                    non-provability or unenforceability of those
                                    amounts in any insolvency or other
                                    proceedings (including interest accruing
                                    after the commencement of any insolvency or
                                    other proceedings)

             SECURITIES             the securities described in Part 2 of the
                                    Schedule

1.2   Headings in this Agreement are inserted for convenience only and shall be
      ignored in construing this Agreement. Unless the context otherwise
      requires, words denoting the singular number only shall include the plural
      and vice versa.

                                                                               3
<PAGE>
1.3   Any discretion or power which may be exercised or any determination which
      may be made hereunder by the Trustee may (save as otherwise provided
      herein) be exercised or made in its absolute and unfettered discretion.

1.4   References to "this Agreement", "Clause" or a "Schedule" are references to
      this Agreement or a clause in or schedule of it.

1.5   References to statutes and/or statutory provisions shall be construed as
      referring to such statutes or statutory provisions as respectively
      replaced amended extended or consolidated.

1.6   The expression "person" shall be construed to include references to any
      person, firm, company, partnership, corporation or any agency thereof.

1.7   Any references herein to any document shall be construed as a reference to
      such document as the same may be amended, supplemented, varied,
      substituted, novated or assigned.

1.8   Any reference to the Company, the Debtor, the Secured Creditors, the
      Trustee or any other party shall include a reference to any successor
      company and permitted assigns.

1.9   For the purposes of the Law, the Trustee shall be considered to be the
      "secured party", the Debtor shall be considered to be the "debtor" and an
      Enforcement Event shall be considered to be an "event of default", unless
      otherwise specified in this Agreement.

1.10  Unless otherwise defined in this Agreement, capitalised words appearing in
      this Agreement shall have the meanings given to such terms in the
      Intercreditor Agreement.

2.    INTERCREDITOR AGREEMENT

2.1   Notwithstanding any provision to the contrary contained herein, the
      parties agree that this Agreement is subject in all respects to the terms
      of the Intercreditor Agreement and for the avoidance of doubt, in the
      event of any inconsistency, the provisions of the Intercreditor Agreement
      shall prevail, provided that the terms of the Intercreditor Agreement are
      not contrary to the Law.

2.2   The parties hereto each acknowledge that the Trustee, when acting
      hereunder, shall be acting in accordance with and subject to the terms of
      the Intercreditor Agreement.

3.    CREATION OF SECURITY INTEREST IN THE SECURITIES

3.1   For the purpose of securing the discharge of the Secured Obligations, the
      Debtor:-

      3.1.1 assigns and transfers to the Trustee all its interest in the
            Securities, all income derived from the Securities and all rights
            attaching to the Securities; and

      3.1.2 acknowledges and confirms delivery to the Trustee of the
            certificates or documents of title to the Securities,

      to the intent that a security interest in the Securities in favour of the
      Trustee is created pursuant to the Law.

3.2   Subject to Clause 4, the security interest created pursuant to this
      Agreement shall include all dividends, income or interest from time to
      time paid on the Securities and all rights, moneys or property accruing or
      offered at any time by way of redemption, bonus, splitting, preference,
      option or otherwise to or in respect of the Securities.

                                                                               4
<PAGE>
3.3   The Debtor will at the request of the Trustee execute or procure the
      execution of legal transfers of the Securities to the Trustee or otherwise
      as the Trustee directs but in the event of any such transfer being
      effected the Trustee shall not be liable for any loss occasioned by any
      exercise or non-exercise of rights attached to such transferred Securities
      or by any failure to forward or report to the Debtor any notice or other
      communication received in respect of such transferred Securities.

4.    DIVIDENDS AND VOTING RIGHTS

4.1   Prior to the occurrence of an Enforcement Event and at any time when no
      Enforcement Event is continuing, the Debtor shall be entitled to:

      4.1.1 retain all dividends, interest and other monies arising from the
            Securities; and

      4.1.2 exercise all voting rights in relation to the Securities provided
            that the Debtor shall not exercise such voting rights in any manner
            which would constitute a Default or an Event of Default under the
            Indentures (as such terms are defined in the Indentures).

4.2   Subject to Clause 7, the Trustee may, upon the occurrence of an
      Enforcement Event and at any time thereafter while such Enforcement Event
      is continuing, at its discretion (in the name of the Debtor or otherwise
      and without any further consent or authority from the Debtor):

      4.2.1 exercise (or refrain from exercising) any voting rights in respect
            of any of the Securities;

      4.2.2 transfer any of the Securities into the name of such nominee(s) of
            the Trustee as it shall require; and

      4.2.3 exercise (or refrain from exercising) the powers and rights
            conferred on or exercisable by the legal or beneficial owner of any
            of the Securities, including the right to concur or participate in:

            4.2.3.1 the reconstruction, amalgamation, sale or other disposal of
                    the Company or any of its assets or undertaking (including
                    the exchange, conversion or reissue of any shares or
                    securities as a consequence thereof),

            4.2.3.2 the release, modification or variation of any rights or
                    liabilities attaching to the Securities, and

            4.2.3.3 the exercise, renunciation or assignment of any right to
                    subscribe for any shares or securities

            in each case in such manner and on such terms as the Trustee may
            think fit, and the proceeds of any such action shall form part of
            the Securities.

4.3   In this Clause 4, "Enforcement Event" shall have the meaning given to such
      term in the Intercreditor Agreement.

5.    CONTINUING SECURITY

5.1   The security interest created pursuant to this Agreement shall continue in
      full force and effect until released or otherwise terminated in accordance
      with this Clause 5.1. The Trustee shall, at the cost of the Debtor,
      release and cancel the security constituted by this Agreement and procure
      the reassignment to the Debtor of the property and assets assigned to the
      Trustee pursuant to this Agreement in accordance with the terms and

                                                                               5
<PAGE>
      subject to the conditions and circumstances set out in the Intercreditor
      Agreement and without recourse to, or any representation or warranty by,
      the Trustee or any of its nominees.

5.2   Upon the release or termination of the security interest created pursuant
      to this Agreement in accordance with Clause 5.1 the Trustee shall furnish
      to the Debtor a duly completed certificate of discharge.

6.    REPRESENTATIONS, WARRANTIES AND UNDERTAKINGS BY THE DEBTOR

6.1   The Debtor represents and warrants to the Trustee that it is:

      6.1.1 the sole beneficial owner of the Securities; and

      6.1.2 the sole legal (except for one Ordinary Share of L1 in the Company
            which is registered in the name of Associated Electrical Industries
            Holdings Limited ("AEIHL") and held by AEIHL as nominee for the
            Debtor) and beneficial owner of all the Securities;

      free from any Security (as such term is defined in the Intercreditor
      Agreement) except as created by this Agreement.

6.2   The Debtor represents and warrants to the Trustee that the Securities are
      fully paid up.

6.3   The Debtor further undertakes to deliver to or to the order of the Trustee
      all certificates of title to any shares or other securities in the Company
      issued after the date of this Agreement ("New Securities") whether or not
      forming part of the Securities, and agrees that to the extent that such
      New Securities do not form part of the Securities, the Debtor will, at its
      own cost, as soon as practicable, execute a security interest agreement
      (in form and substance similar to this Agreement) over the New Securities
      in favour of the Trustee.

7.    POWERS OF THE TRUSTEE UPON ENFORCEMENT

7.1   At any time after the occurrence of an Enforcement Event, and the Trustee
      (acting on instructions received pursuant to the terms of the
      Intercreditor Agreement) giving notice to the Issuer thereof and subject
      to the giving of notice by the Trustee in accordance with the Law, the
      security interest created pursuant to this Agreement shall become
      immediately enforceable and the Trustee may in its absolute discretion:-

      7.1.1 exercise all its rights and powers under the Law;

      7.1.2 pay any calls or other payments due from time to time in respect of
            the Securities or payable in respect of any rights attaching to the
            Securities;

      7.1.3 exercise any rights attaching to the Securities for the purpose of
            preserving the value of the Securities;

      7.1.4 in addition to any lien or right to which the Trustee may be
            entitled by law, without notice set off the whole or any part of the
            Secured Obligations against any amount or other obligation
            (contingent or otherwise) owing by the Trustee to the Debtor.

7.2   The Trustee may exchange or convert to the Required Currency any currency
      held or received.

                                                                               6
<PAGE>
7.3   Subject to Clause 7.1, the Securities shall be applied by the Trustee in
      the manner set out in the Intercreditor Agreement.

8.    RESTRICTIONS ON CHARGING AND DISPOSAL

      The Debtor shall not, except as not expressly prohibited under the terms
      of the Indentures:-

8.1   create or permit to arise any mortgage, charge, lien or other security
      interest on the Securities or any interest in or part of the Securities;
      or

8.2   sell or attempt to sell or otherwise dispose of the Securities or any
      interest in or part of the Securities.

9.    POWER OF ATTORNEY

9.1   The Debtor by way of security irrevocably appoints the Trustee and each
      Delegate severally to be its attorney (the "Attorney") and in its name, on
      its behalf and as its act and deed to execute, deliver and perfect all
      documents and do all things which the Attorney may consider to be required
      or desirable for:

      9.1.1 carrying out any obligation imposed on the Debtor by this Agreement
            (including the execution and delivery of any notices, deeds,
            charges, assignments or other security and any transfers of the
            Securities); and

      9.1.2 enabling the Trustee and each Delegate to exercise, or delegate the
            exercise of, any of the rights, powers and authorities conferred on
            them by or pursuant to this Agreement or by law (including, after
            the occurrence of an Enforcement Event, the exercise of any right of
            a legal or beneficial owner of the Securities).

9.2   The Debtor shall ratify and confirm all things done and all documents
      executed by any Attorney in the exercise or purported exercise of all or
      any of his powers.

9.3   The Debtor shall indemnify the Attorney and keep the Attorney indemnified
      against any and all costs, claims, and liabilities which the Attorney may
      incur as a result of anything done by the Attorney in the proper exercise
      of any of the powers conferred, or purported to be conferred, on him or
      her by this Agreement unless such cost, claim or liability arises as a
      result of the negligence or wilful misconduct of the Attorney.

10.   PRESERVATION OF OTHER SECURITY AND RIGHTS AND FURTHER ASSURANCE

10.1  The security created pursuant to this Agreement is in addition to any
      other security present or future held by the Trustee for the Secured
      Obligations and shall not merge with or prejudice such other security or
      any contractual or legal rights of the Trustee.

10.2  The security created by this Agreement shall not be affected by any other
      security held by the Trustee in respect of the Secured Obligations being
      void or unenforceable.

10.3  The Debtor shall do all such acts and execute all such documents
      (including assignments, transfers, mortgages, charges, notices and
      instructions) as the Trustee may specify (and in such form as the Trustee
      may require in favour of the Trustee or its nominee(s)):

      10.3.1 to perfect the security created or intended to be created in
            respect of the Securities or for the exercise of all rights, powers
            and remedies of the Trustee provided by or pursuant to this
            Agreement or by the Law;

                                                                               7
<PAGE>
      10.3.2 to confer on the Trustee security over the Securities; and/or

      10.3.3 to facilitate the realisation of the Securities.

11.   NOTICES

11.1  Any notice or demand by the Trustee may effectually be made by notice in
      writing to the Debtor under the hand of any one of the Trustee's officers
      served in accordance with Section 13 of the Law.

11.2  Any notice of default required to be given pursuant to Section 7(3) of the
      Law shall be deemed to have been received by the Debtor:-

      11.2.1 when delivered to the Debtor, or

      11.2.2 when left at the Debtor's proper address, or

      11.2.3 if posted to the Debtor at the Debtor's proper address on the day
             immediately following the posting of such notice notwithstanding
             that it be returned undelivered.

11.3  For the purpose of this Agreement the term "proper address" shall mean:-

      11.3.1 the address of the Debtor as provided in this Agreement; and/or

      11.3.2 such other address as the Debtor shall have notified in writing to
             the Trustee in advance; and/or

      11.3.3 the Address for Service.

11.4  Subject as otherwise provided in this Agreement, each communication to be
      made under this Agreement shall be made and delivered in accordance with
      the provisions of the Intercreditor Agreement.

12.   EXPENSES, COSTS AND TAXES

12.1  EXPENSES

      The Debtor shall, from time to time and promptly on demand by the Trustee
      reimburse to the Trustee all costs and expenses (including legal fees) on
      a full indemnity basis together with any applicable VAT incurred by the
      Trustee and any Delegate (provided that in relation to sub-clause 12.1.1
      of this Clause 12, such costs and expenses must be properly incurred) in
      connection with:

      12.1.1. the execution, release and discharge of this Agreement and the
              security created or intended to be created in respect of the
              Securities and perfection of the Security contemplated in this
              Agreement or in any such documents or forming part of the Security
              created or intended to be created in respect of the Securities;

      12.1.2. the actual or contemplated exercise, preservation and/or
              enforcement of any of the rights, powers and remedies of, or the
              performance of the duties and obligations of, the Trustee or any
              Delegate, or any amendment or waiver in respect of this Agreement;

      12.1.3. the foreclosure of any Securities; and

                                                                               8
<PAGE>
      12.1.4. the preservation and/or enforcement of the Security created or
              intended to be created in respect of the Securities;

              which shall carry interest from the date of such demand until so
              reimbursed at the rate and on the basis as mentioned in clause
              18.4 (Interest on Demands) of the Intercreditor Agreement.

12.2  TAXES

      The Debtor shall pay, promptly on demand of the Trustee all stamp,
      registration, notarial and other similar Taxes or fees paid or payable by
      the Trustee in connection with any action taken or contemplated by or on
      behalf of the Trustee for perfecting, enforcing, releasing, cancelling,
      reassigning or resolving any doubt concerning, or for any other purpose in
      relation to this Agreement, any amendment thereto, any transfer and/or
      assignment of the rights and/or obligations under the same or the Security
      created or intended to be created in respect of the Securities and shall,
      from time to time, indemnify the Trustee promptly on demand against any
      liabilities, costs, claims and expenses resulting from any failure to pay
      by the Debtor or any delay by the Debtor in paying any such Taxes or fees.

13.   GENERAL

13.1  Each of the provisions of this Agreement shall be severable and distinct
      from one another and if one or more of such provisions is invalid or
      unenforceable the remaining provisions shall not in any way be affected.

13.2  The Trustee may assign and transfer all or any of its rights and
      obligations under this Agreement in accordance with the Intercreditor
      Agreement. The Trustee shall be entitled to disclose such information
      concerning the Debtor and this Agreement as the Trustee considers
      appropriate to any actual or proposed direct or indirect successor or to
      any person to whom information may be required to be disclosed by any
      applicable law.

13.3  This Agreement may be executed in any number of counterparts and by
      different parties hereto in separate counterparts, each of which when so
      executed shall be deemed to be an original and all of which when so
      executed shall constitute one and the same binding agreement between the
      parties.

14.   GOVERNING LAW AND JURISDICTION

14.1  This Agreement shall be governed by and construed in accordance with the
      laws of Guernsey.

14.2  For the benefit of the Trustee the Debtor irrevocably submits to the
      jurisdiction of the Guernsey Courts and the Debtor irrevocably agrees that
      a judgment in any proceedings in connection with this Agreement by the
      Guernsey Courts shall be conclusive and binding upon the Debtor and may be
      enforced against the Debtor in the Courts of any other jurisdiction. The
      Trustee shall also be entitled to take proceedings in connection with this
      Agreement against the Debtor in the Courts of any country in which the
      Debtor has assets or in any other Courts of competent jurisdiction.

14.3  The Debtor irrevocably waives:-

      14.3.1 any objection which the Debtor may now or in the future have to the
             Guernsey Courts or other Courts referred to in Clause 14.2 as a
             venue for any proceedings in connection with this Agreement; and

                                                                               9
<PAGE>
      14.3.2 any claim which the Debtor may now or in the future be able to make
             that any proceedings in the Guernsey Courts or other Courts
             referred to in Clause 14.2 have been instituted in an inappropriate
             forum.

IN WITNESS whereof this Agreement has been duly executed.

PATRICIA A HOFFMAN
SIGNED by PATRICIA A HOFFMAN
duly authorised signatory
for and on behalf of
FS FINANCE CORP

R D RANCE
SIGNED by R D RANCE
duly authorised signatory
for and on behalf of
THE LAW DEBENTURE TRUST CORPORATION P.L.C.

                                                                              10
<PAGE>
                                    SCHEDULE

                              PART 1 - THE COMPANY

Bruton Street Overseas Investments Limited

Registered Number: 33433
Registered Office: 1 Le Marchant Street, St. Peter Port, Guernsey

                             PART 2 - THE SECURITIES

The entire issued share capital of the Company, being

      -     1,000 Cumulative Preference Shares of L0.01 each registered in the
            name of the Debtor;

      -     99 Ordinary Shares of L1 each registered in the name of the Debtor;

      -     1 Ordinary Share of L1 registered in the name of Associated
            Electrical Industries Holdings Limited

all of which are fully paid up.

                                                                              11

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