UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 6-K
REPORT OF FOREIGN PRIVATE ISSUER
PURSUANT TO RULE 13a-16 OR 15d-16
UNDER THE SECURITIES EXCHANGE ACT OF 1934
For the month of January , 2007
SPIRENT COMMUNICATIONS plc
_____________________________________________________________________
(Translation of registrant's name into English)
Spirent House, Crawley Business Quarter, Fleming Way, Crawley, West Sussex
RH10 9QL, UK.
_____________________________________________________________________
(Address of principal executive offices)
Indicate by check mark whether the registrant files or will file annual reports
under cover Form 20-F or Form 40-F.
Form 20-F X Form 40-F.....
Indicate by check mark whether the registrant by furnishing the information
contained in this Form is also thereby furnishing the information to the
Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.
Yes ..... No X
If "Yes" is marked, indicate below the file number assigned to the registrant
in connection with Rule 12g3-2(b): 82- ________
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
Signatures
Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorized.
______MICHAEL ANSCOMBE______
(Registrant)
Date: 9 January, 2007 By ____/s/ Michael Anscombe____
(Signature)*