Holding(s) in Company

Spirent Communications PLC
10 March 2008


TR-1: Notifications 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 notification (yes/no)                                                          

An acquisition or disposal of voting rights                             Yes                    

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):______________                                    No

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 under13.

5. Date of transaction (and date on which the threshold
is crossed or reached if different):                     06/03/08

6. Date on which issuer notified:                        07/03/08

7. Threshold(s) that is/are crossed or reached:          Below 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 shares Number of      Number of       Number of voting rights       Percentage of voting 
rights
If possible use                      voting rights  shares
ISIN code

                                                                    Direct          Indirect      Direct     Indirect   
    Indirect
GB0004726096        39,437,558       39,437,558     38,520,235      456,000      38,064,235        0.059%     4.921%



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
                                                               exercised/converted)


Total (A+B)


Number of voting rights                              Percentage of voting rights
38,520,235                                           4.980%




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           A/c 05577                  350,000
                                     Littledown Nominees Ltd           A/c 05576                5,020,000
                                     Littledown Nominees Ltd           A/c 07197                  456,000
                                     Littledown Nominees Ltd           A/c 10479                   25,837
                                     Littledown Nominees Ltd           A/c 07203                  268,000
                                     Littledown Nominees Ltd           A/c 21667                  103,000
                                     Littledown Nominees Ltd           A/c 34789                  362,000
                                     Littledown Nominees Ltd           A/c 10491               17,949,271
                                     Littledown Nominees Ltd           A/c 10488                1,500,000
                                     Littledown Nominees Ltd           A/c 10489               11,134,327
                                     Littledown Nominees Ltd           A/c 10490                1,155,000
                                     Ameriprise                        A/c                        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]




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