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 March, 2005

                                   SPIRENT 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- ________ 





                                 SCHEDULE 10

                   NOTIFICATION OF MAJOR INTERESTS IN SHARES


1. Name of company

SPIRENT PLC


2. Name of shareholder having a major interest

DEUTSCHE BANK AG


3. Please state whether notification indicates that it is in respect of holding
of the shareholder named in 2 above or 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

SHAREHOLDER IN 2 ABOVE


5. Number of shares / amount of stock acquired

UNKNOWN


6. Percentage of issued class

UNKNOWN


7. Number of shares / amount of stock disposed

-


8. Percentage of issued class

-


9. Class of security

ORDINARY SHARES OF 3.3333 PENCE EACH


10. Date of transaction

NOT NOTIFIED


11. Date company informed

30 MARCH 2005


12. Total holding following this notification

32,041,235


13. Total percentage holding of issued class following this notification

3.33%


14. Any additional information




15. Name of contact and telephone number for queries

MICHAEL ANSCOMBE - 01293 767672


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

MICHAEL ANSCOMBE - ASSISTANT COMPANY SECRETARY


Date of notification

31 MARCH 2005


The FSA does not give any express or implied warranty as to the accuracy of 
this document or material and does not accept any liability for error or 
omission. The FSA is not liable for any damages (including, without limitation,
damages for loss of business or loss of profits) arising in contract, tort or 
otherwise from the use of or inability to use this document, or any material 
contained in it, or from any action or decision taken as a result of using this 
document or any such material.


 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.

                                               ______LUKE THOMAS______

                                                     (Registrant)  
 
Date 31 March, 2005                        By   ____/s/ Luke Thomas____

                                                    (Signature)*