Holding(s) in Company

Spirent Communications PLC
09 January 2007


                   NOTIFICATION OF MAJOR INTERESTS IN SHARES


1. Name of listed company

SPIRENT COMMUNICATIONS PLC


2. Name of shareholder with a major interest

SUN LIFE ASSURANCE COMPANY OF CANADA (UK) 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


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

ROY Nominees                                                                                    22,782,261
ROY Nominees                                                                                     4,102,441

TOTAL                                                                                           26,884,702


5. Number of shares / amount of stock acquired

3,392,482


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

0.38%


7. Number of shares / amount of stock disposed

N/A


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

N/A


9. Class of security

ORDINARY SHARES OF 3 & 1/3 PENCE EACH


10. Date of transaction

5 JANUARY 2007


11. Date company informed

9 JANUARY 2007


12. Total holding following this notification

26,884,702  ORDINARY SHARES


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)

3.04%


14. Any additional information

THE SHAREHOLDER HELD A REPORTABLE HOLDING PRIOR TO 21 JULY 2006, BUT THEN CEASED
TO HOLD A REPORTABLE HOLDING AS OF 21 JULY 2006. THE SHAREHOLDER NOW HOLDS A
REPORTABLE HOLDING OF 26,884,702 SHARES (3.04%) AS OF 8 JANUARY 2007.


15. Name of contact and telephone number for queries

MICHAEL ANSCOMBE - 01293 767676


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

9 JANUARY 2007




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