Holding(s) in Company

Spirent Communications PLC
02 October 2007


TR-1:               Notification of major interests in shares


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

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

An acquisition or disposal of voting rights
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                 X                     
Other (please specify):

3. Full name of person(s) subject to the notification            Prudential plc group of companies
   obligation:

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

                                                                  MAGIM HSBC GIS NOM(UK) SALI
                                                                  NORTRUST NOMINEE LTD A/C MHF01
                                                                  NORTRUST NOMINEE LTD A/C MHJ01
                                                                  NORTRUST NOMINEE LTD A/C MKB01
                                                                  NORTRUST NOMINEE LTD A/C MKM01
                                                                  NORTRUST NOMS LTD
                                                                  NORTRUST NOMS LTD A/C PUF01
                                                                  NORTRUST NOMS LTD A/C PUI01
                                                                  NORTRUST NOMS LTD A/C PUQ01
                                                                  NORTUST NOMS LTD A/C PUR01
                                                                  PRUCLT HSBC GIS NOM(UK) PAC AC
                                                                  PRUCLT HSBC GIS NOM(UK) PPL AC
                                                                  PRUCLT HSBC GIS NOM(UK) EQBF AC
                                                                  PRUCLT HSBC GIS NOM(UK) MNBF AC
                                                                  PRUCLT HSBC GIS NOM(UK) PENE AC

5. Date of the transaction (and date on which the threshold is    26 September 2007
   crossed or reached if different):

6. Date on which issuer notified:                                 1 October 2007

7. Threshold(s) that is/are crossed or reached:                   See item 13

8. Notified details:




A: Voting rights attached to shares
Class/type of       Situation previous to the   Resulting situation after the triggering transaction(i)
shares              Triggering transaction
                     Number of     Number of       Number of    Number of voting rights     % of voting
(if possible using     Shares    Voting Rights      shares                                    rights
the ISIN CODE)                        viii          Direct         Direct      Indirect   Direct  Indirect
                                                                                  xi
GB0004726096        72,548,273   72,548,273        72,548,273      72,548,273             8.43%


B: Financial Instruments
Resulting situation after the triggering transaction
 Type of financial   Expiration date   Exercise/ Conversion     Number of voting rights     % of voting
     instrument                            Period/ Date         that may be acquired if        rights
                                                                   the instrument is
                                                                 exercised/ converted.
        N/A          N/A                        N/A                     N/A                      N/A


Total (A+B)
Number of voting rights                            % of voting rights
72,548,273                                         8.43%










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

Prudential plc (parent Company)

M&G Group Limited (wholly owned subsidiary of Prudential plc)

M&G Limited (wholly owned subsidiary of M&G Group Limited)

M&G Investment Management Limited (wholly owned subsidiary of M&G Limited)

The Prudential Assurance Company Limited (wholly owned subsidiary of Prudential plc)


Proxy Voting:

10. Name of the proxy holder:                                      N/A
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:                  As per 5.1.2 the 5% threshold for non-exempt holdings has been
                                             crossed triggering this notification.
14. Contact name:                            Emma Thompson

                                             M&G Investment Management Limited
15. Contact telephone number:                020 7548 2293


Additional Information


Contact at Issuer: Michael Anscombe, Company Secretary, Spirent Communications plc

Telephone [phone]



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