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                                                                    EXHIBIT 4.56

[CLIFFORD CHANGE PUNDER LOGO]
                                                                  CONFORMED COPY

                           MARCONI COMMUNICATIONS GMBH

                                   AS PLEDGOR

                                       AND

                   THE LAW DEBENTURE TRUST CORPORATION p.l.c.

                         AS PLEDGEE AND SECURITY TRUSTEE

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                   LIMITED PARTNER'S INTEREST PLEDGE AGREEMENT

                           relating to the interest in

              Marconi Communications Software Systems GmbH & Co. KG
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                                  NOTARIAL DEED

                                                        ROLL OF DEED NO. 45/2003

Recorded

at Basel this 15th day of May 2003

Before me, the undersigned

                                Dr. Thomas Gelzer

                                  notary public

with official offices in Basel (Switzerland) appeared today the following
persons:

1.       Ms. Muriel Krebs, born on March 31, 1978 having her business address at
         Aeschenvorstadt 4, 4010 Basel (Switzerland) personally known to the
         notary.

2.       Ms. Stefanie Brennwald, born on February 8, 1978, having her business
         address at Aeschenvorstadt 4, 4010 Basel (Switzerland) personally known
         to the notary.

The person appearing to 1. declared to make the following declarations not in
her own name but, excluding any personal liability, for and on behalf of

         MARCONI COMMUNICATIONS GMBH, a limited liability company organised
         under the laws of the Federal republic of Germany, having its business
         address at Backnang, which is registered in the commercial register
         (Handelsregister) of the local court (Amtsgericht) of Backnang under
         HRB 1563 (the "PLEDGOR"),

         Presenting a fax copy of the power of attorney dated May 13, 2003,
         promising to furnish the original as soon as possible.

The person appearing to 2. declared to make the following declarations not in
her own name but, excluding any personal liability, for and on behalf of

         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 (as defined
         below) (the "SECURITY TRUSTEE" or the "PLEDGEE"),

         presenting a fax copy of the power of attorney dated May 14, 2003,
         promising to furnish the original as soon as possible.

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Neither the Notary nor the proxies assume any liability as to the validity
and/or the scope of the powers of attorney presented.

The aforementioned original powers of attorney will be attached to this deed in
copies which are herewith certified.

The Notary convinced himself that the persons appearing are in adequate command
of the English language and declared that he is in command of the English
language as well.

The persons appearing stated that the parties represented by them requested that
this instrument be recorded in the English language.

On being asked whether there had been any prior involvement by the notary in
terms of paragraph 3 sub-paragraph 1 No. 7 of the German Notarisation Act
(Beurkundungsgesetz) the provisions of which had been explained by the Notary,
the persons appearing said that there had been no such prior involvement.

I.       Requesting its notarisation, the persons appearing then declared the
         following:

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INTEREST PLEDGE AGREEMENT

BETWEEN:

1.       Marconi Communications GmbH, a limited liability company organised
         under the laws of the Federal Republic of Germany, having its business
         address at Backnang, which is registered in the commercial register
         (Handelsregister) of the local court (Amtsgericht) of Backnang under
         HRB 1563 (the "PLEDGOR"); and

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

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 (the "SENIOR NOTES");

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

                  (together the "NOTES"); 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 Pledgor) as amended from time to time (the "SECURITY
         TRUST AND INTERCREDITOR DEED").

(C)      The Pledgor has agreed to grant a first ranking pledge over its limited
         partner's interest in the Company (as defined below) as security for
         the payment and

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         discharge of the Secured Obligations (as defined below) subject to the
         terms and conditions set out herein.

NOW, IT IS AGREED as follows:

1.       DEFINITIONS AND LANGUAGE

1.1      In this Agreement:

         "COMPANY" means Marconi Communications Software Systems GmbH & Co. KG,
         a limited partnership (Kommanditgesellschaft) organised under the laws
         of the Federal Republic of Germany having its business address at
         Backnang, Germany, which is registered in the commercial register
         (Handelsregister) of the local court (Amtsgericht) of Backnang under
         HRA 898.

         "CONTINUING" in relation to an Enforcement Event, shall be construed as
         a reference to 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 waived
         in writing.

         "DEFAULT" means any event or circumstance specified as Default in any
         of the Relevant Documents (as defined below).

         "ENFORCEMENT EVENT" means the acceleration of any Obligations (as
         defined below) (other than Obligations arising under the New Bonding
         Facility Agreement (as defined below)) or any declaration that any
         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) or any failure by any
         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.

         "ESCROW AGREEMENT" means the escrow agreement dated on or about the
         date of the Security Trust and Intercreditor Deed and made between,
         inter alia, the Security Trustee and the Issuer establishing and
         setting out the terms and conditions of each of the escrow accounts.

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         "EVENT OF DEFAULT" means any event or circumstance specified as an
         Event of Default in any of the Relevant Documents (as defined below).

         "GUARANTEE" means any guarantee of any of the Obligations.

         "INITIAL SECURITY DOCUMENTS" means the Guarantees guaranteeing the
         Obligations and the security documents, each to be dated on or before
         the dates on which the Senior Notes and the Junior Notes are first
         originally issued.

         "NEW BONDING FACILITY AGREEMENT" means the GBP 50,000,000 (or the
         equivalent in other currencies) committed multicurrency revolving
         bonding facility agreement dated 27 March 2003 and entered into by,
         inter alios, the Issuer, Marconi Bonding Limited and HSBC Bank plc for
         the issuance of bonds, guarantees, letters of credit, indemnities and
         similar instruments.

         "OBLIGATIONS" means 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 any Obligor under the Relevant Documents, both actual and
         contingent and 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).

         "OBLIGORS" means the Issuer, any entity being a party to the Security
         Trust and Intercreditor Deed as guarantor, including the Pledgor, and
         any entity which accedeS to the Security Trust and Intercreditor Deed
         as guarantor and an "OBLIGOR" means any of them.

         "RELEVANT DOCUMENTS" means the Security Trust and Intercreditor Deed,
         any agent/trustee accession letter relating to the Security Trust and
         Intercreditor Deed any bank accession letter relating to the New
         Bonding Facility Agreement, any guarantor accession letter relating to
         any Guarantee, the Indentures, the Escrow Agreement, the Notes, the New
         Bonding Facility Agreement, the

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         Security Documents, any fee letter and any additional remuneration fee
         letter pursuant to the Security Trust and Intercreditor Deed and any
         notices issued and any other documents or agreements entered into in
         connection with or relating to such documents.

         "SECURITY DOCUMENTS" means (i) the Initial Security Documents securing
         the Obligations, (ii) any other pledge agreements, security agreements,
         mortgages, deeds of trust and other agreements, instruments and
         documents entered into from time to time by the Issuer or any
         subsidiary of the Issuer creating or granting any Guarantee, indemnity
         or security in favour of any of the secured creditors or the Security
         Trustee, as trustee for the secured creditors, as security for any of
         the Obligations and (iii) any other agreements, instruments and
         documents executed and delivered pursuant to any of the foregoing, in
         the case of each of clauses (i) through (iii), as amended, modified,
         restated or supplemented from time to time.

         "SECURED OBLIGATIONS" has the meaning given to it under Clause 3.

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

1.2      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.       PLEDGED SHARES

2.1      The limited partner's interest in the Company has an aggregate nominal
         value of EUR 766.937,82 (in words: Euro seven hundred sixty-six
         thousand nine hundred thirty-seven and eighty-two) (the "EXISTING
         INTEREST"). There are no other limited partner`s interests in the
         Company.

2.2      The Pledgor is the sole owner of the Existing Interest free from any
         encumbrances.

2.3      The Existing Interest is fully paid up. There is no obligation for the
         Pledgor to make additional contributions.

3.       SECURED OBLIGATIONS

         The pledges hereunder are constituted in order to secure together with
         other security granted by the Pledgor the prompt and complete
         satisfaction of any and all obligations (present and future, actual and
         contingent) which are (or are

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         expressed to be) or become owing by the Pledgor to the Pledgee under
         the Relevant Documents (including, but not limited to the parallel
         obligations of the Pledgor 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 Pledgor to the secured creditors or any of them) (the
         "SECURED OBLIGATIONS") up to an aggregate amount of EUR 170 million.

4.       PLEDGE

4.1      The Pledgor hereby pledges to the Pledgee the Existing Interest and all
         additional limited partner's interest in the capital of the Company
         (irrespective of their nominal value) which the Pledgor may acquire in
         the future (the "FUTURE INTEREST" and, together with the Existing
         Interests the "INTERESTS") together with all ancillary rights and
         claims associated with the Interests as more particularly specified in
         Clause 5 hereof (each a "PLEDGE" and together the "PLEDGES").

4.2      The Pledgee hereby accepts the Pledges.

4.3      The validity and effect of each of the Pledges shall be independent
         from the validity and the effect of the other Pledges created
         hereunder.

4.4      Each of the Pledges is in addition, and without prejudice, to any other
         security the Pledgee may now or hereafter hold in respect of the
         Secured Obligations.

4.5      The Pledges shall rank ahead of any other security interest or third
         party right now in existence or created in the future in or over any of
         the Interests.

4.6      For the avoidance of doubt, the parties agree that nothing in this
         Agreement shall exclude a transfer of all or part of the Pledges
         created hereunder by operation of law upon the transfer or assignment
         (including by way of assumption (Vertragsubernahme)) of all or part of
         the Secured Obligations by the Pledgee to a future pledgee.

5.       SCOPE OF THE PLEDGES

5.1      The Pledges constituted by this Agreement include:

         (a)      the present and future rights to receive:

                  (i)      profits payable in relation to the Interests
                           (Gewinnanspruch), if any and, in particular but not
                           limited to, any and all rights and claims arising in
                           connection with the capital accounts (Kapitalkonten);
                           and

                  (ii)     liquidation proceeds (Liquidationserlos), redemption
                           proceeds (Einziehungsentgelt), repaid capital in case
                           of a capital decrease,

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                           any compensation in case of termination (Kundigung)
                           and/or withdrawal (Austritt) of a partner of the
                           Company, the surplus in case of surrender
                           (Preisgabe), any claim to a distribution-quote
                           (Auseinandersetzungsanspruch) and all other pecuniary
                           claims (geldwerte Forderungen) associated with the
                           Interests; and

         (b)      all other rights and benefits attributable to the Interests.

5.2      Notwithstanding that the profits attributable are pledged hereunder,
         the Pledgor shall be entitled to receive and retain, but only to the
         extent not expressly prohibited by the Relevant Documents, all payments
         of profits attributable to the Interests whether in cash, by the issue
         of any loan note or debt instrument or in specie in respect of the
         Interests until the occurrence of an Enforcement Event and at any time
         when no Enforcement Event is continuing.

6.       EXERCISE OF MEMBERSHIP RIGHTS

         The membership rights, including the voting rights, attached to the
         Interests remain with the Pledgor. The Pledgor, however, shall at all
         times until the full satisfaction of all Secured Obligations or the
         release of the Pledges exercise its membership rights, including its
         voting rights, to the extent that such exercise would not constitute a
         Default or an Event of Default.

7.       ENFORCEMENT OF THE PLEDGES

7.1      At any time after the occurrence of an Enforcement Event which is
         continuing and if the requirements set forth in Section 1204 et seq. of
         the German Civil Code (Burgerliches Gesetzbuch) with regard to the
         enforcement of any of the Pledges are met (Pfandreife), in particular,
         if any of the Secured Obligations has become due and payable, then in
         order to enforce the Pledges (or any of them), the Pledgee may, in its
         discretion, at any time thereafter avail itself of all rights and
         remedies that a pledgee has upon default of a pledgor under the laws of
         the Federal Republic of Germany.

7.2      Notwithstanding Section 1277 of the German Civil Code, the Pledgee is
         entitled to exercise its rights without obtaining enforceable judgment
         or other instrument (vollstreckbarer Titel) by way of public auction.

7.3      Each Pledgor hereby expressly agrees that five (5) business days' prior
         written notice to the relevant Pledgor of the place and time of any
         such public auction shall be sufficient. The public auction may take
         place at any place in the Federal Republic of Germany designated by the
         Pledgee.

7.4      If the Pledgee, should seek to enforce the Pledges under Clause 7
         hereof, the Pledgor shall, at its own expense, render forthwith all
         necessary assistance in

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         order to facilitate the prompt sale of the Interests or any part
         thereof and/or the exercise by the Pledgee, of any other right it may
         have as Pledgee.

7.5      If the Pledges are enforced, no rights of the Pledgee shall pass to the
         relevant Pledgor by subrogation or otherwise unless and until all of
         the Secured Obligations have been satisfied and discharged in full. In
         the case of enforcement, Section 1225 of the German Civil Code shall
         not apply. Until full discharge of the Secured Obligations, the Pledgee
         shall be entitled to treat all enforcement proceeds as additional
         collateral for the Secured Obligations, or to seek satisfaction from
         such proceeds at any time.

7.6      Following satisfaction of the requirements for enforcement under Clause
         7.1 hereof, all subsequent payments of profits attributable to the
         Interests and all payments based on similar ancillary rights attributed
         to the Interests may be applied by the Pledgee, in satisfaction in
         whole or in part of the Secured Obligations or treated as additional
         collateral.

7.7      Even if the requirements for enforcement referred to under Clause 7.1
         above are met, the Pledgee shall not, whether as proxy or otherwise, be
         entitled to exercise the voting rights attached to the Interests.

7.8      The Pledgee, may, in its sole discretion, determine which of several
         security interests, if applicable, shall be used to satisfy the Secured
         Obligations.

7.9      Each Pledgor hereby expressly waives all defences of revocation
         (Einrede der Anfechtbarkeit) and set-off (Einrede der Aufrechenbarkeit)
         pursuant to Sections 770, 1211 of the German Civil Code.

7.10     With respect to the enforcement of the Pledges the Pledgee will take
         into consideration the legitimate interest of the Pledgor.

8.       LIMITATION OF PLEDGE

8.1      The right to enforce the Pledges 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 Pledgor (other
         than any of the Pledgor's subsidiaries), at all times be limited to an
         amount equal to the Pledgor'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 Pledgor's liabilities (the calculation of which shall
         take into account 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 Pledgor (the "NET ASSETS").

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8.2      The Pledgor shall realise, to the extent legally permitted and, in
         respect of the Pledgor, commercially justifiable, in a situation where
         the Pledgor 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 Pledgor's business (betriebsnotwendig).

8.3      The Security Trustee shall enforce any Pledge created hereunder against
         the Pledgor in accordance with the following procedure:

            (i)   The Pledgor shall, following a notification by the Security
                  Trustee to the Pledgor that an Enforcement Event has occurred
                  and that the Security Trustee intends to enforce the Pledges,
                  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
                  Pledgor under the Pledges 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 Pledgor under the Pledges, 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 Pledgor 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 Pledgor that it
                  intends to enforce the Pledges.

            (iv)  If the Pledgor 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
                  Pledges against the Pledgor without limitation.

9.      UNDERTAKINGS OF THE PLEDGOR

        During the term of this Agreement, the Pledgor undertakes to the
        Pledgee:

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9.1      not to take, or participate in, any action which results or might
         result in the Pledgor's loss of ownership of all or part of the
         Interests and any other transaction which would have the same result as
         a sale, transfer, encumbrance or other disposal of the Interests or
         which would for any other reason be inconsistent with the security
         interest of the Pledgee or the security purpose (as described in Clause
         3 hereof) except in each case to the extent such action is not
         expressly prohibited for the Issuer and its subsidiaries under the
         Indentures; and

9.2      insofar as additional documents, declarations or actions (including
         making all filings and registrations) are necessary for the creation,
         perfection, protection or maintenance of the Pledges created (or
         purported to be created) hereunder (or any of them) in favour of the
         Pledgee 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 Pledges created (or purported to
         be created) hereunder (or any of them), the Pledgor shall at the
         Security Trustee's request, made in accordance with the Security Trust
         and Intercreditor Deed, enter into or provide such documents, make such
         declarations and/or undertake such actions at the Pledgor's cost and
         expense.

10.      EXPENSES, COSTS AND TAXES

10.1     EXPENSES

         The Pledgor 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 value added tax or any other tax of similar nature
         incurred by the Security Trustee and any representative, agent or
         advisor (hereinafter a "DELEGATE") (provided that in relation to
         sub-clause (i) of this Clause 10, 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
                  Pledges 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
                  Pledges;

            (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 Pledges; and

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

         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.

10.2     TAXES

         The Pledgor shall pay, promptly on demand of the Security Trustee all
         stamp, registration, notarial and other similar tax, duty, levy,
         impost, assessment or other governmental charge of whatever nature
         (including penalties, interest and other liabilities related thereto)
         (hereinafter "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
         Pledges and shall, from time to time, indemnify the Security Trustee
         promptly on demand against any liabilities, costs, claims and expenses
         resulting from any failure to pay by the Pledgor or any delay by the
         Pledgor in paying any such Taxes or fees.

11.      DURATION AND INDEPENDENCE

11.1     This Agreement shall remain in full force and effect until complete
         satisfaction of the Secured Obligations. The Pledges shall not cease to
         exist if the Pledgor has only temporarily discharged the Secured
         Obligations.

11.2     This Agreement shall create a continuing security and no change,
         amendment, or supplement whatsoever in the Relevant Documents or in any
         document or agreement related to any of the Relevant Documents shall
         affect the validity or the scope of this Agreement nor the obligations
         which are imposed on the Pledgor pursuant to it.

11.3     This Agreement is independent from any other security or guarantee
         which may have been or will be given to the Pledgee. None of such other
         security shall prejudice, or shall be prejudiced by, or shall be merged
         in any way with this Agreement.

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12.      RELEASE (PFANDFREIGABE)

12.1     Upon complete and irrevocable satisfaction of the Secured Obligations,
         the Pledgee 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 representation or
         warranty by, the Security Trustee or any of its nominee) at the cost
         and expense of the Pledgor confirm the release of the Pledges
         (Pfandfreigabe) to the Pledgor as a matter of record. For the
         advoidance of doubt, the parties are aware that upon full and complete
         satisfaction of the Secured Obligations the Pledges, due to their
         accessory nature (Akzessoritat) cease to exist by operation of German
         law.

12.2     At any time when the total value of the aggregate security granted by
         the Pledgor 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 Pledgee on demand of the
         Pledgor 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 representation or
         warranty by, the Security Trustee or any of its nominee) 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.

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, such provision shall as to such 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 or enforceable provision which comes as close as possible to the
         original 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
         Pledgee, 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.

13.3     In particular, the Pledges shall not be affected and shall in any event
         extend to 100% of the Pledgor's limited partner's interests
         (Kommanditanteile) in the

                                     - 11 -

<PAGE>

         Company even if the number or nominal value of the Existing Interests
         or the aggregate share capital of the Company as stated in Clause 2 are
         inaccurate or deviate from the actual facts.

14.      AMENDMENTS; WAIVER

         This Agreement may be amended, modified or waived only in writing
         unless notarial form by operation of law is required. 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):

         For the Pledgor:             Marconi Communications GmbH
                                         Address:    Gerberstra ss 33
                                                     D-71522 Backnang

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

         For the Pledgee :            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

                                     - 12 -

<PAGE>

         (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).

15.4     Save for the notice pursuant to Section 16 of the German Limited
         Liability Companies Act (Gesetz betreffend die Gesellschaften mit
         beschrankter Haftung) and Section 1280 of the German Civil Code
         (Burgerliches Gesetzbuch) any notice given under or in 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 constitutional,
         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.

                                     - 13 -

<PAGE>

16.4     NON-EXCLUSIVE JURISDICTION

         This Clause 16 is for the benefit of the Pledgee only. As a result it
         does not prevent the Pledgee from taking proceedings relating to a
         Dispute ("PROCEEDINGS") in any other courts with jurisdiction. To the
         extent allowed by law, the Pledgee 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 Pledgor and this Agreement as the Security 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.

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.

The Notary advised the persons appearing

         -        that a pledge is a security instrument of strictly accessory
                  nature (which means that it comes into legal existence only
                  if, to the extent that, and as long as, the underlying secured
                  claims do in fact exist, and that the owners of the secured
                  claims and the pledgee must be identical);

         -        that there is no bona fide creation, acquisition nor ranking
                  of a pledge of shares (which means that the pledgee is not
                  protected if the shares purported to be pledged do not exist,
                  have been previously transferred to a third party, or have
                  been previously encumbered for the benefit of a third party);
                  and

         -        that the English original version of this Agreement will not
                  be acceptable for enforcement but will have to be translated,
                  by a certified translator, into German for such purposes.

                                     - 14 -

<PAGE>

The Notary is hereby instructed to give notice of this Agreement and the Pledges
of the rights pursuant to Clause 4 (Pledge) and Clause 5 (Scope of the Pledges)
to the Company by means of forwarding to the Company a certified copy of this
Agreement.

The above Agreement including the Schedule was read aloud by the Notary to the
persons appearing, approved by them and signed in their own hand as follows:

Basel, this 15th (fifteenth) day of May, 2003 (two thousand and three)

MS MURIEL KREBS

MS STEFANIE BRENNWALD

DR THOMAS GELZER (Signed and Sealed)

Allg. Prot. Nr. 45/2003

                                     - 15 -

<PAGE>

                                   SCHEDULE 1

                              PARTNERS' RESOLUTION

                                     - 16 -

<PAGE>

<TABLE>
<S>                                                                    <C>
        PROTOKOLL EINER GESELLSCHAFTERVERSAMMLUNG                     PROTOCAL OF A PARTNERS' MEETING

                                                              Wir,/We,

                                                     Marconi Communications GmbH

eingetragen im Handelsregister des Amtsgerichts Backnang unter Nr.     registered in the commercial register (Handelsregister) of
HRB 1563                                                               the Local Court (Amtsgericht) of Backnang under registration
                                                                       no. HRB 1563

als alleinige Komanditistin                                                                           as the sole limited partner of

                                                               und/and

                                 Marconi Communications Software Systems Verwaltungsgesellschaft mbH

eingetragen im Handelsregister des Amtsgerichts Backnang unter Nr.     registered in the commercial register (Handelsregister) of
HRB 1447                                                               the Local Court (Amtsgericht) of Backnang under registration
                                                                       no. HRB 1447

als die alleinige Komplementarin (die "KOMPLEMENTaRIN") der            as the sole general partner (the "GENERAL PARTNER") of

                                        MARCONI COMMUNICATIONS SOFTWARE SYSTEMS GMBH & Co. KG

eingetragen im Handelsregister des Amtsgerichts Backnang unter der     registered in the commercial register (Handelsregister) of
Registernummer HRA 898                                                 the Local Court (Amtsgericht) of Backnang under registration
                                                                       no. HRA 898

                                                (die "GESELLSCHAFT" / the "COMPANY").

halten hiermit unter Verzicht auf unter Verzicht auf alle              hold hereby, waiving all and any requirements of form or
gesetzlichen und satzungsmassigen Frist- und Formvorschriften eine     notice imposed by applicable law or the articles of the
Gesellschafter-versammlung ab.                                         Company, partners' meeting.

Die Marconi Corporation plc beabsichtigt, schuldrechtlich              Marconi Corporation plc intends to issue USD equivalent of
erstrangige, garantierte und besicherte Inhaberschuldverschreibungen   GBP 450,000,000.00 guaranteed and secured senior notes due
fallig 2008 in Hohe eines US Dollar Betrag, der aquivalent zu GBP      2008 (referred to as "SENIOR NOTES") and USD 300,000,000.00
450.000.000,00 ist, (im folgenden "ERSTRANGIGE                         plus USD equivalent of GBP 117,270,000.00 guaranteed and
                                                                       secured
</TABLE>

<PAGE>

<TABLE>
<S>                                                                    <C>
SCHULDVERSCHREIBUN-GEN" genannt) und USD 300.000.000,00 plus dem       Junior notes due 2008 (referred to as "JUNIOR
aquivalenten US Dollar Betrag von GBP 117.270.000,00 schuldrechtlich   NOTES").
zweitrangige, garantierte und besicherte
Inhaberschuldver-schreibungen fallig 2008 (im folgenden
"ZWEITRANGIGE SCHULDVERSCHREIBUNGEN" ge-nannt) zu begeben.

Des weiteren schlossen Marconi Corporation plc, Marconi Bonding        In addition, on 27th March, 2003, Marconi Corporation plc,
Limited und andere Mitglieder der Gruppe am 27. Marz 2003 einen        Marconi Bonding Limited and other members of the Marconi
Vertrag zur Aufnahme eines neuen Avalkredit in Hohe von GBP            group entered into a GBP 50,000,000.00 new bonding facility
50.000.000,00, der in Form von Obligation, Burgschaften,               for the issuance of bonds, guarantees, letter of credits,
Akkreditiven, Garantien und ahnlichen Instrumenten ausgereicht         indemnities and similar instruments (referred to as "NEW
werden soll, ab (im folgenden "AVALKREDIT" genannt).                   BONDING FACILITY").

Unter anderem zur Besicherung (i) der Anspruche der Law Debenture      In order to secure, among others, (i) the claims of Law
Trust Company of New York als Treuhander und der Inhaber der           Debenture Trust Company of New York as note trustee and the
erstrangigen Schuldverschreibungen unter den erstrangigen              noteholders under the Senior Notes, (ii) the claims of
Schuldverschreibungen, (ii) der Anspruche von JPMorgan Chase Bank      JPMorgan Chase Bank as note trustee and the noteholders under
als Treuhander und der Inhaber der zweitrangigen                       the Junior Notes; and (iii) the claims of HSBC Bank plc as
Schuldverschreibungen unter den zweitrangigen Schuldverschreibungen    security trustee and agent, the issuing banks and others
und (iii) der Anspruche der HSBC Bank plc als Sicherheitentreuhander   under New Bonding Facility, Marconi Communications GmbH
und Agent, der ausstellenden Banken und anderer unter dem Avalkredit   intends to pledge its present and future limited partner's
beabsichtigt Marconi Communications GmbH, ihre gegenwartigen und       interest in the Company in favour of The Law Debenture Trust
kunftigen Kommanditanteil an der Gesellschaft zugunsten von The Law    Corporation p.l.c. as security trustee.
Debenture Trust Corporation p.l.c. als Sicherheitentreuhander zu
verpfanden.

Dies zur Kenntnis wird hiermit folgender Gesellschafterbeschluss       Acknowledging the above the following partners' resolution is
gefasst:                                                               hereby passed:

1)  Die Marconi Communications GmbH stimmt hiermit als alleinige       1)  Marconi Communications GmbH as sole shareholder of the
    Kommanditistin der                                                 Company hereby consents
</TABLE>

<PAGE>

<TABLE>
<S>                                                                    <C>
    Gesellschaft der Verpfandung der                                      to a pledge over all present and
    gegenwartigen und kunftigen Kommandit-anteile an der                  future limited partner's interest in the Company in favour
    Gesellschaft zugunsten von The Law Debenture Trust Corporation        of The Law Debenture Trust Corporation p.l.c. as security
    p.l.c. als Sicherheitentreuhander zu.                                 trustee.

2)  Die Gesellschaft des weiteren ist zum AbschluB des globalen        2) The Company is, furthermore, entitled to enter into the
    Lizenzvertrages mit anderen Mitglieder der Marconi Gruppe             global licence agreement with other member of the Marconi
    berechtigt.                                                           group.

Weitere Beschlusse wurden nicht gefasst.                               No further resolutions were taken.

Die Komplementarin hat nach dem Gesellschaftsvertrag der               Pursuant to the Partnership Agreement the General Partner has
Gesellschaft kein Stimmrecht und unterzeichnet dieses Protokoll der    no voting right and therefore signs this Protocol of the
Gesellschafterversammlung daher nur zur Dokumentation ihres            Partners' Meeting only to prove its waiver of the
Verzichts auf die Einhaltung der gesetzlichen und satzungsmassigen     requirements of form or notice imposed by applicable law or
Frist- und Formvorschriften und ihrer Teilnahme an der                 the articles of the Company and its participation in the
Gesellschafterversammlung.                                             partners' meeting.
</TABLE>

                         Backnang, den / this 14.05.2003

                           MARCONI COMMUNICATIONS GMBH

              als alleinige Kommanditistin/as sole limited partner

                                    Durch/By:

          S. DICK                                      E. PROKSCHI

        Steffen Dick                                  Edmund Prokschi

Geschaftsfuhrer/Managing Director              Geschaftsfuhrer/Managing Director

<PAGE>

                                    M GARTNER

                                    M Gartner

                        Geschaftsfuhrer/Managing Director
       MARCONI COMMUNICATIONS SOFTWARE SYSTEMS VERWALTUNGSGESELLSCHAFT MBH
              als alleinige Komplementarin/as sole general partner

                                    Durch/By:

           M. MAYR                                         R. BISCHOF

         Markus Mayr                                     Rainer Bischof

Geschaftsfuhrer/Managing Director              Geschaftsfuhrer/Managing Director