Holding(s) in Company

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARES

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

Spirent Communications plc

2 Reason for the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

√

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

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

An event changing the breakdown of voting rights

Other (please specify):

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

Aviva plc & its subsidiaries

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

Registered Holder:

BNY Norwich Union Nominees Limited  3,838,966*

Chase (GA Group) Nominees Limited  24,604,945*

Chase Nominees Limited 687,721*

Vidacos Nominees Limited 36,556*

*denotes direct interest

Chase Nominees Limited 1,397,583

Vidacos Nominees Limited 260,926

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

03 August 2010

6. Date on which issuer notified:

05 August 2010

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

>5% to

8. Notified details:

A: Voting rights attached to shares viii, ix

Class/type of shares

if possible using the ISIN CODE

Situation previous to the triggering transaction

Resulting situation after the triggering transaction

Number of Shares

Number of Voting Rights

Number of shares

Number of voting rights

% of voting rights x

Direct

Direct xi

Indirect xii

Direct

Indirect

Ordinary Shares GB0004726096

42,461,120

42,461,120

30,826,697

29,168,188

1,658,509

 4.32%

0.24%

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Expiration date xiii

Exercise/ Conversion Period xiv

Number of voting rights that may be acquired if the instrument is exercised/ converted.

% of voting rights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transaction

Type of financial instrument

Exercise price

Expiration date xvii

Exercise/ Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

30,826,697

4.56%

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

The voting rights are managed and controlled by Aviva Investors Global Services Limited, with the following chain of controlled undertakings:-

Aviva Investors Global Services Limited:

·; Aviva plc (Parent Company)

·; Aviva Group Holdings Limited (wholly owned subsidiary of Aviva plc)

·; Aviva Investors Holdings Limited (wholly owned subsidiary of Aviva Group Holdings Limited)

·; Aviva Investors Global Services Limited (wholly owned subsidiary of Aviva Investors Holdings Limited)

Proxy Voting:

10. Name of the proxy holder:

See Section 4

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:

Figures are based on the total number of voting rights of 675,514,244.

14. Contact name:

Neil Whittaker

15. Contact telephone number:

01603 684420

C: Additional information

Contact at Issuer: Michelle Balch, Assistant Company Secretary, Spirent Communications plc

Telephone: 01293 767676