Holding(s) in Company

Spirent PLC
17 March 2006

                   NOTIFICATION OF MAJOR INTERESTS IN SHARES

1. Name of listed company

SPIRENT PLC

2. Name of shareholder with a major interest

FIDELITY INTERNATIONAL LIMITED

3. Please state whether notification indicates that regarding the holding of the
shareholder named in 2 above; in respect of a non-beneficial interest; or in the
case of an individual holder if it is a holding of that person's spouse or
children under the age of 18

SHAREHOLDER IN 2 ABOVE AND ITS DIRECT AND INDIRECT SUBSIDIARIES, BEING 
NON-BENEFICIAL HOLDERS

4. Name of the registered holder(s) and, if more than one holder, the number of
shares held by each of them

JP MORGAN BOURNEMOUTH (FPM)                                          1,873,889
NORTHERN TRUST LONDON (FPM)                                          1,136,000
MELLON BANK (FPM)                                                      578,900
BANK OF NEW YORK BRUSSELS (FPM)                                        480,600
STATE STR BK AND TR CO LNDN (FPM)                                      411,800
BANKERS TRUST LONDON (FPM)                                             321,200
MIDLAND SECURITIES SERVICES (FPM)                                      144,700
CLYDESDALE BANK PLC (FPM)                                               46,300
JP MORGAN BOURNEMOUTH (FISL)                                        24,209,187
BROWN BROS HARRIMN LTD LUX (FIL)                                    29,277,928
JP MORGAN BOURNEMOUTH (FIL)                                            990,000
BANK OF NEW YORK BRUSSELS (FIL)                                        162,200
NORTHERN TRUST LONDON (FIL)                                             83,700
JP MORGAN, BOURNEMOUTH (FII)                                         1,395,500
BNP PARIBAS, PARIS (FIGEST)                                          2,021,500
TOTAL                                                               63,133,404

FPM = Fidelity Pension Management
FISL = Fidelity Investment Services Limited
FIL = Fidelity International Limited
FII = Fidelity Investments International
FIGEST = Fidelity Gestion

5. Number of shares / amount of stock acquired

-

6. Percentage of issued class (any treasury shares held by the listed company
should not be taken into account when calculating percentage)

-

7. Number of shares / amount of stock disposed

NOT KNOWN

8. Percentage of issued class (any treasury shares held by the listed company
should not be taken into account when calculating percentage)

NOT KNOWN

9. Class of security

ORDINARY SHARES OF 3.3333 PENCE EACH

10. Date of transaction

NOT KNOWN

11. Date company informed

17 MARCH 2006

12. Total holding following this notification

63,133,404

13. Total percentage holding of issued class following this notification (any
treasury shares held by the listed company should not be taken into account when
calculating percentage)

6.51%

14. Any additional information

ON 28 FEBRUARY 2006 THE SHAREHOLDER REPORTED TO THE COMPANY THAT IT HAD REDUCED 
ITS HOLDING IN THE COMPANY TO 75,458,113 SHARES (7.81%).

15. Name of contact and telephone number for queries

MICHAEL ANSCOMBE - 01293 767672

16. Name and signature of duly authorised company official of the listed company
responsible for making this notification

MICHAEL ANSCOMBE - DEPUTY COMPANY SECRETARY

Date of notification

17 MARCH 2006


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