Holding(s) in Company

Spirent Communications PLC
26 March 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)


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): Decrease in the number of total voting rights in Spirent 
Communications plc resulting from the on-going share buy-back programme       X


                                                                             

3. Full name of person(s) subject to notification obligation:

  (i) Sherborne Investors LP;
 (ii) Sherborne Investors GP, LLC
(iii) Craig L. McKibben;
 (iv) Gerard L. Eastman, Jr.; and
  (v) Edward Bramson.


                                                                                     

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

Person named in 3 above             Shareholder                         No of shares

(i-iv)                              Hanover Nominees Limited            130,250,000 ordinary shares
                                                                        (aggregate)

(v)                             (a) Hanover Nominees Limited            130,250,000 ordinary shares
                                                                        (aggregate)

                                (b) Merrill Lynch, Pierce, Fenner &          20,000 ordinary shares
                                    Smith, Inc
                                                                                    

5. Date of transaction (and date on which the threshold is
crossed or reached if different):                        March 20, 2008
                                                                                    

6. Date on which issuer notified:                        March 26, 2008
                                                                       

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

   (i) Sherborne Investors LP - 17% (aggregate);
  (ii) Sherborne Investors GP, LLC - 17% (aggregate);
 (iii) Craig L. McKibben -17% (aggregate);
  (iv) Gerard L. Eastman, Jr. - 17% (aggregate); and
   (v) Edward Bramson - 17% (aggregate).

Please note, for the purposes of this TR-1 notification, the only entities 
which have triggered a new notification obligation under the Disclosure and
Transparency Rules are those entities noted in 3 above.

None of Hayden Investors Partners, LLC, Hayden Investors Partners II, LLC, 
Sherborne Strategic Fund A, LLC or Sherborne Strategic Fund B, LLC have reached,
exceeded or fallen below a relevant threshold as a result of Spirent 
Communications plc's recent buy-back programme.


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 rights
If possible use    shares        voting rights shares
ISIN code
                                               Direct         Direct          Indirect       Direct         Indirect

Ordinary shares    130,250,000   130,250,000   130,250,000         N/A        130,250,000        N/A          17.03%
ISIN: GB0004726096


Ordinary shares         20,000        20,000        20,000      20,000                N/A      0.003%            N/A
ISIN: GB0004726096



B: Financial Instruments


Resulting situation after the triggering transaction


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

        N/A                 N/A                 N/A                    N/A                    N/A


Total (A+B)


Number of voting rights                              Percentage of voting rights


130,270,000 (aggregate)                              17.03%


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


Edward Bramson is the managing member and Craig L. McKibben and Gerard L.
Eastman, Jr. are members of Sherborne Investors GP, LLC.  Sherborne Investors
GP, LLC is the general partner of Sherborne Investors LP, which is the managing
member of each of the following funds (all of which hold ordinary shares in the
issuer through Hanover Nominees Limited):


(i)  Hayden Investors Partners, LLC (45,685,845 ordinary shares - approximately
5.97% -no new individual notification required, see response to 7. above);


(ii) Hayden Investors Partners II, LLC (40,844,268 ordinary shares -
approximately 5.34% - no new individual notification required, see response to
7. above);


(iii)Sherborne Strategic Fund A, LLC (29,644,000 ordinary shares - approximately
3.88% -  no new individual notification required, see response to 7. above); and


(iv) Sherborne Strategic Fund B, LLC (14,075,887 ordinary shares - approximately
1.84% - no individual notification required, see response to 7. above).


Edward Bramson holds 20,000 further shares through Merrill Lynch, Pierce, Fenner
& Smith, Inc.


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:                          N/A


14 Contact name:                                     Craig L. McKibben


15. Contact telephone name:                          [phone]




Additional information

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

Telephone:         [phone]


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