SPIRENT PLC ANNOUNCES NOTIFICATION OF MAJOR INTERESTS IN SHARES

Market Wire, March, 2006

              NOTIFICATION OF MAJOR INTERESTS IN SHARES

1. Name of listed company

SPIRENT PLC

2. Name of shareholder with a major interest

BARCLAYS PLC

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

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

  Registered Holder                 Account Designation       Holding

  BARCLAYS CAPITAL NOMINEES                                  -126,801
  LIMITED
  BARCLAYS CAPITAL NOMINEES                                   -76,469
  LIMITED
  BARCLAYS CAPITAL NOMINEES                                   554,239
  LIMITED
  BARCLAYS CAPITAL NOMINEES                                 2,003,740
  LIMITED
  Barclays Trust Co & Others                                    8,077
  BNP PARIBAS                                                  51,000
  BOISS NOMINEES LTD                            4224361       594,977
  CHASE NOMINEES LTD                              16376       527,631
  CHASE NOMINEES LTD                              20947    29,775,272
  CHASE NOMINEES LTD                              21359     1,483,196
  CHASE NOMINEES LTD                              28270       307,679
  CHASE NOMINEES LTD                              28270       908,176
  CIBC MELLON GLOBAL SECURITIES                                42,140
  Gerrard Nominees Limited                       642367        13,000
  Gerrard Nominees Limited                       650668        13,000
  Gerrard Nominees Limited                       653035        13,000
  Gerrard Nominees Limited                       660632         6,000
  Gerrard Nominees Limited                       660758        35,000
  Gerrard Nominees Limited                       660851        30,000
  Greig Middleton Nominees                                    200,787
  Limited (GM1)
  INVESTORS BANK AND TRUST CO.                                221,432
  INVESTORS BANK AND TRUST CO.                                 22,464
  INVESTORS BANK AND TRUST CO.                                 56,359
  INVESTORS BANK AND TRUST CO.                              1,770,097
  INVESTORS BANK AND TRUST CO.                                699,748
  INVESTORS BANK AND TRUST CO.                                 54,686
  JP MORGAN (BGI CUSTODY)                         16331       268,775
  JP MORGAN (BGI CUSTODY)                         16341     2,160,554
  JP MORGAN (BGI CUSTODY)                         16341       560,581
  JP MORGAN (BGI CUSTODY)                         16344       687,727
  JP MORGAN (BGI CUSTODY)                         16345     1,158,601
  JP MORGAN (BGI CUSTODY)                         16400     9,479,907
  JP MORGAN (BGI CUSTODY)                         18409       791,821
  JPMorgan Chase Bank                                         555,319
  JPMorgan Chase Bank                                         399,337
  Mellon Trust - US CUSTODIAN /                                81,846
  MELLON TRUST OF NEW ENGLAND                                  81,368
  NORTHERN TRUST BANK - BGI SEPA                              136,835
  NORTHERN TRUST BANK - BGI SEPA                              120,848
  NORTHERN TRUST BANK - BGI SEPA                               35,400
  R C Greig Nominees Limited                                  921,916
  R C Greig Nominees Limited a/c                              705,551
  AK1
  R C Greig Nominees Limited a/c                               97,464
  BL1
  R C Greig Nominees Limited a/c                               24,646
  CM1
  R C Greig Nominees Limited GP1                               50,096
  R C Greig Nominees Limited SA1                               31,232
  STATE STREET TRUST OF CANADA -                               77,145
  The Northern Trust Company - U                               54,943
  Total                                                    57,670,342

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

HOLDING AS AT 23 MARCH 2006

11. Date company informed

28 MARCH 2006

12. Total holding following this notification

57,670,342

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)

5.95%

14. Any additional information

SHAREHOLDER PREVIOUSLY REPORTED A SHAREHOLDING OF 105,727,030 (10.91%) ON 14 MARCH 2006.

15. Name of contact and telephone number for queries