Holding(s) in Company

Spirent Communications PLC
30 January 2008


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

Other (please specify): A sale of shares has caused a subsidiary of Prudential plc to cross 11%     X
triggering this notification

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

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                    25 January 2008
crossed or reached if different):

6. Date on which issuer notified:                                                 29 January 2008

7. Threshold(s) that is/are crossed or reached:                                         11%


8. Notified details:

A: Voting rights attached to shares

Class/type of shares  Situation previous to the     Resulting situation after the triggering transaction
                      Triggering transaction
(if possible using      Number of      Number of       Number of    Number of voting rights % of voting rights
the ISIN CODE)           Shares      Voting Rights      shares
                                                        Direct          Direct     Indirect  Direct   Indirect
GB0004726096          86,649,004    86,649,004      86,024,004      86,024,004              11.01%
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
86,024,004                                         11.01%



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:                  M&G Investment Management Limited (wholly owned subsidiary of M&
                                             G Limited) has dropped below a 11% notifiable interest
                                             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: Michelle Balch, Assistant Company Secretary, Spirent Communications plc
Telephone: [phone]



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