Holding(s) in Company

Spirent Communications PLC
07 December 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                                                  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             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

                                                                    PPL UK EQUITY 350 PASSIVE FUND

                                                                      PPL UK EQUITY GROWTH FUND

                                                                    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            5th December 2007
crossed or reached if different):
6. Date on which issuer notified:                                         7th December 2007
7. Threshold(s) that is/are crossed or reached:                                  11%
8. Notified details:




A: Voting rights attached to shares
Class/type of       Situation previous to the   Resulting situation after the triggering transaction
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)                                      Direct          Direct     Indirect   Direct  Indirect
GB0004726096        86,031,355   86,031,355     89,531,355      89,531,355               11.13%


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
89,531,355                                         11.13%







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:
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]




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