Holding(s) in Company

TR-1: Notifications 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

yes

An acquisition or disposal of qualifying financial instruments which may result in the acquisition of shares already issued to which voting rights are attached

no

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments

no

An event changing the breakdown of voting rights

yes

Other (please specify):

no

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

 Standard Life Investments Ltd

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

 Vidacos Nominees

5. Date of the transaction (and date on which the threshold is crossed or reached):

22 December 2010

6. Date on which issuer notified:

23 December 2010

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

6%

8: Notified Details

A: Voting rights attached to shares

Class/type of share If possible use ISIN code

GB0004726096

Situation previous to the triggering transaction

Number of shares

Number of voting rights

42,119,630

42,119,630

Resulting situation after the triggering transaction

Number of shares

Number of voting rights

Percentage ofvoting rights

Direct

Indirect

Direct

Indirect

39,930,407

23,170,140

16,760,267

3.420%

2.474%

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Expiration date

Exercise/ conversion period/date

No. of voting rights that may be acquired(if the instrument exercised/converted)

Percentage of voting rights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Exerciseprice

Expirationdate

Exercise/Conversionperiod

Number of votingrights instrumentrefers to

% of voting rights

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

 39,930,407

5.894%

Proxy Voting:

10. Name of the proxy holder:

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

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

13. Additional information:

14. Contact name:

[email protected] Life Investments Ltd

15. Contact telephone number:

(0131) 245 6565