Holding(s) in Company

Spirent Communications PLC
24 January 2008



TR-1: Notification of Major Interests in Shares

                                                                    

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


2. Reason for notification (yes/no)                                 Yes

An acquisition or disposal of voting rights                         No

An acquisition or disposal of financial instruments which may result in the acquisition
of shares already issued to which voting rights are attached        No

An event changing the breakdown of voting rights                    No

Other (please specify):______________                    
                                                         

3. Full name of person(s) subject to notification
obligation:                                              Ameriprise Financial, Inc and its group


                                                           

4. Full name of shareholder(s) (if different from 3):    See additional information under 13                      



5. Date of transaction (and date on which the
threshold is crossed or reached if different):           22/01/08
                                                                         

6. Date on which issuer notified:                        23/01/08
                                                                         

7. Threshold(s) that is/are crossed or reached:          Above 5%




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 Percentage of voting
If possible use shares       voting       shares                               rights
ISIN code                    rights

                                          Direct       Direct      Indirect    Direct       Indirect


 GB0004726096       N/A          N/A       39,437,558    456,000   38,981,558     0.058%       4.979%



B: Financial Instruments


Resulting situation after the triggering transaction


Type of financial    Expiration date      Exercise/ conversion No. of voting rights  Percentage of voting
instrument                                period/date          that may be acquired  rights
                                                               (if the instrument is
                                                              exercised/converted)



Total (A+B)


Number of voting rights                              Percentage of voting rights


39,437,558                                           5.037%


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

Ameriprise Financial, Inc., which controls the voting rights of

Threadneedle Asset Management Holdings Ltd, which controls the voting rights of

Threadneedle Asset Management Ltd, Threadneedle International Ltd and Threadneedle Pensions Ltd


Proxy Voting:

10. Name of proxy holder:                            N/A


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


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


13. Additional information:                          Registered owner:

                                                     Littledown Nominees Ltd (05577)            350,000

                                                     Littledown Nominees Ltd (05576)          5,020,000

                                                     Littledown Nominees Ltd (07197)            456,000

                                                     Littledown Nominees Ltd (10479)             25,837

                                                     Littledown Nominees Ltd (07203)            268,000

                                                     Littledown Nominees Ltd (21667)            103,000

                                                     Littledown Nominees Ltd (34789)            362,000

                                                     Littledown Nominees Ltd (10491)         19,681,461

                                                     Littledown Nominees Ltd (10488)          1,500,000

                                                     Littledown Nominees Ltd (10489)         10,319,460

                                                     Littledown Nominees Ltd (10490)          1,155,000

                                                     Ameriprise                                 196,800

14 Contact name:                                     Company Secretary, Threadneedle Group


15. Contact telephone name:                          0207 464 5000


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