Source: London Stock Exchange plc.

Spirent Communications PLC announces Holding(s) in Company

Crawley, UK -- (MARKET WIRE) -- April 5, 2007 --


TR-1(i):           NOTIFICATION OF MAJOR INTERESTS IN SHARES 

1. Identity of the issuer or the underlying 
   issuer of existing shares to which 
   voting rights are attached(ii):          Spirent Communications plc

2. Reason for the notification    (please tick the appropriate box or 
   boxes)

   An acquisition or disposal of voting rights            x

An acquisition or disposal of financial 
instruments which may result in the 
acquisition of shares already issued to 
which voting rights are attached

An event changing the breakdown of voting rights                                             

Other (please specify):________________________     

3. Full name of person(s) subject to the 
   notification obligation (iii):     Aviva plc and its subsidiaries


4. Full name of shareholder(s) (if 
   different from 3.)(iv):            Registered Holder:

                                      BNY Norwich Union Nominees 
                                      Limited                 7,707,920*

                                      Chase GA Group Nominees 
                                      Limited                12,737,120*

                                      Chase Nominees Limited  1,406,381*

                                      CUIM Nominee Limited    5,107,701*

                                      Vidacos Nominees Limited  250,659*

                                     * denotes direct interest

5. Date of the transaction (and 
   date on which the threshold is           2 April 2007
   crossed or reached if different)(v):

6. Date on which issuer notified:           4 April 2007

7. Threshold(s) that is/are crossed         2% to 3% Change at 
   or reached:                              Direct Interest level

8. Notified details:


A: Voting rights attached to shares

Class/type of   Situation previous to the  Resulting situation after the
shares          Triggering transaction     triggering transaction (vii)
                (vi)
if possible
using the ISIN
CODE
                Number of  Number of Voting
                Shares     Rights viii

Ordinary Shares Below 3%   Below 3%
GB0004726096



Class/type of   Resulting situation after the triggering transaction (vii)
shares          
                
if possible
using the ISIN
CODE

                 Number of           Number of 
                    shares        voting rights ix     % of voting rights
                                  
                     Direct     Direct x   Indirect xi Direct  Indirect

Ordinary Shares  27,209,781   27,209,781   Not         3.08%   Not
GB0004726096                               disclosable         disclosable



B: Financial Instruments

Resulting situation after the triggering transaction xii

Type of         Expiration  Exercise/
financial       date xiii   Conversion Period/
instrument                  Date xiv

                            N/A



B: Financial Instruments

Resulting situation after the triggering transaction xii

Number of voting rights   % of
that may be acquired if   voting
the instrument is         rights
exercised/ converted.


Total (A+B)
Number of voting rights                   % of voting rights


27,209,781                                3.08%



9. Chain of controlled undertakings through 
   which the voting rights and/or the 
   financial instruments are effectively 
   held, if applicable xv:                 See Section 4


Proxy Voting:

10. Name of the proxy holder:              See Section 4


11. Number of voting rights proxy holder 
    will cease to hold:                    N/A

12. Date on which proxy holder will 
    cease to hold voting rights:           N/A

13. Additional information:                Figures are based on a total 
                                           number of voting rights of
                                           882,644,785.

14. Contact name:                          Diane Thirkettle

15. Contact telephone number:              01603 687803


C:        Additional information


Contact at Issuer: Warren Nash, Share Plans Manager, 
Spirent Communications plc


Telephone:          01293 767676


--------------------------

NOTES:

(i)   This form is to be sent to the issuer or underlying issuer and to
      be filed with the competent authority.

(ii)  Either the full name of the legal entity or another method for
      identifying the issuer or underlying issuer, provided it is 
      reliable and accurate.

(iii) This should be the full name of (a) the shareholder; (b) the
      person acquiring, disposing of or exercising voting rights in the 
      cases provided for in DTR5.2.1 (b) to (h);  (c) all the parties to 
      the agreement referred to in DTR5.2.1 (a), or (d) the direct or 
      indirect holder of financial instruments entitled to acquire shares 
      already issued to which voting rights are attached, as appropriate.

In relation to the transactions referred to in points DTR5.2.1 (b) to
(h), the following list is provided as indication of the persons who 
should be mentioned:

-   in the circumstances foreseen in  DTR5.2.1 (b), the person that
    acquires the voting rights and is entitled to exercise them under the 
    agreement and the natural person or legal entity who is transferring 
    temporarily for consideration the voting rights;

-   in the circumstances foreseen in DTR 5.2.1 (c), the person holding
    the collateral, provided the person or entity controls the voting 
    rights and declares its intention of exercising them, and person 
    lodging the collateral under these conditions;

-   in the circumstances foreseen in DTR5.2.1(d), the person who has a
    life interest in shares if that person is entitled to exercise the 
    voting rights attached to the shares and the person who is disposing 
    of the voting rights when the life interest is created;

-   in the circumstances foreseen in DTR5.2.1 (e), the parent undertaking 
    and, provided it has a notification duty at an individual level
    under DTR 5.1, under DTR5.2.1 (a) to (d) or under a combination of 
    any of those situations, the controlled undertaking;

-   in the circumstances foreseen in DTR5.2.1 (f), the deposit taker of
    the shares, if he can exercise the voting rights attached to the 
    shares deposited with him at his discretion, and the depositor of the 
    shares allowing the deposit taker to exercise the voting rights at 
    his discretion;

-   in the circumstances foreseen in DTR5.2.1 (g), the person  that
    controls the voting rights;

-   in the circumstances foreseen in DTR5.2.1 (h), the proxy holder, if
    he can exercise the voting rights at his discretion, and the 
    shareholder who has given his proxy to the proxy holder allowing the 
    latter to exercise the voting rights at his discretion.

(iv)Applicable in the cases provided for in DTR 5.2.1 (b) to (h). This
    should be the full name of the shareholder or holder of financial 
    instruments who is the counterparty to the natural person or legal 
    entity referred to in DTR5.2.

(v) The date of the transaction should normally be, in the case of an
    on exchange transaction, the date on which the matching of orders 
    occurs; in the case of an off exchange transaction, date of the 
    entering into an agreement.

The date on which threshold is crossed should normally be the date on 
which the acquisition, disposal or possibility to exercise voting rights 
takes effect (see DTR 5.1.1R (3)). For passive crossings, the date when 
the corporate event took effect.

These dates will usually be the same unless the transaction is subject to 
a condition beyond the control of the parties.

(vi) Please refer to the situation disclosed in the previous 
     notification, In case the situation previous to the triggering 
     transaction was below 3%, please state 'below 3%'.

vii  If the holding has fallen below the minimum threshold , the
     notifying party should not be obliged to disclose the extent of the 
     holding, only that the new holding is less than 3%.

For the case provided for in DTR5.2.1(a), there should be no disclosure of
individual holdings per party to the agreement unless a party individually
crosses or reaches an Article 9 threshold. This applies upon entering
into, introducing changes to or terminating an agreement.

viii Direct and indirect

ix   In case of combined holdings of shares with voting rights attached '
     direct holding' and voting rights 'indirect holdings', please split 
     the voting rights number and percentage into the direct and indirect 
     columns-if there is no combined holdings, please leave the relevant 
     box blank.

X    Voting rights attached to shares in respect of which the notifying
     party is a direct shareholder  (DTR 5.1)

xi   Voting rights held by the notifying party as an indirect
     shareholder (DTR 5.2.1)

xii  If the holding has fallen below the minimum threshold, the notifying
     party should not be obliged to disclose the extent of the holding, 
     only that the new holding is below 3%.

xiii date of maturity / expiration of the finical instrument i.e. the
     date when the right to acquire shares ends.

xiv  If the financial instrument has such a period-please specify the
     period- for example once every three months starting from the (date)

xv   The notification should include the name(s) of the controlled
     undertakings through which the voting rights are held. The 
     notification should also include the amount of voting rights and the 
     percentage held by each controlled undertaking, insofar as 
     individually the controlled undertaking holds 3% or more, and 
     insofar as the notification by the parent undertaking is intended to 
     cover the notification obligations of the controlled undertaking.

xvi  This annex is only to be filed with the competent authority.

xvii Whenever another person makes the notification on behalf of the
     shareholder or the natural person/legal entity  referred to in 
     DTR5.2 and DTR5.3.

**************************************************************************


                      This information is provided by RNS
            The company news service from the London Stock Exchange