Holding(s) in Company

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARESi

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

X

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

Prudential plc group of companies

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

JP MORGAN NOMINEES

 NORTRUST NOMINEE LTD A/C MHF01

NORTRUST NOMINEE LTD A/C MKM01

NORTRUST NOMS LTD

NORTRUST NOMS LTD A/C PUF01

NORTRUST NOMS LTD A/C PUI01

NORTRUST NOMS LTD A/C PUQ01

NORTRUST NOMS LTD A/C PUR01

PRUCLT HSBC GIS NOM(UK) PAC AC

PRUCLT HSBC GIS NOM(UK) PPL AC

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

28 September 2009

6. Date on which issuer notified:

29 September 2009

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

12%

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

GB0004726096

80,864,733

80,864,733

80,997,047

80,997,047

12.01%

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

80,997,047

12.01%

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

Prudential plc (parent Company)

M&G Group Limited (wholly owned subsidiary of Prudential plc)

M&G Limited (wholly owned subsidiary of M&G Group Limited)

M&G Investment Management Limited (wholly owned subsidiary of M&G Limited)

The Prudential Assurance Company Limited (wholly owned subsidiary of Prudential plc)

Proxy Voting:

10. Name of the proxy holder:

N/A

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

N/A

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

N/A

13. Additional information:

Calculations based on a Total Voting Rights figure of 674,198,645.

14. Contact name:

Dipesh Varsani / Mark Thomas

M&G Investment Management Limited

15. Contact telephone number:

020 7548 3261 / 020 7548 3266

C: Additional information

Contact at Issuer: Rachel Whiting, Company Secretary, Spirent Communications plc

Telephone: 01293 767676