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 February 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 11

          NOTIFICATION OF INTERESTS OF DIRECTORS AND CONNECTED PERSONS


1. Name of company

SPIRENT PLC


2. Name of director

JOHN WESTON


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 or in respect of a non-beneficial
interest

IN RESPECT OF THE DIRECTOR'S HOLDING


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

N/A


5. Please state whether notification relates to a person(s) connected with the
director named in 2 above and identify the connected person(s)

N/A


6. Please state the nature of the transaction. For PEP transactions please
indicate whether general/single co PEP and if discretionary/non discretionary

ACQUISITION OF ORDINARY SHARES


7. Number of shares / amount of stock acquired

62,000


8. Percentage of issued class

0.006%


9. Number of shares/amount of stock disposed

N/A


10. Percentage of issued class

N/A


11. Class of security

ORDINARY SHARES OF 3 1/3 PENCE


12. Price per share

67.25 PENCE


13. Date of transaction

25 FEBRUARY 2005


14. Date company informed

25 FEBRUARY 2005


15. Total holding following this notification

1,662,000


16. Total percentage holding of issued class following this notification

0.17%


If a director has been granted options by the company please complete the
following boxes.


17. Date of grant

N/A


18. Period during which or date on which exercisable

N/A


19. Total amount paid (if any) for grant of the option

N/A


20. Description of shares or debentures involved: class, number

N/A


21. Exercise price (if fixed at time of grant) or indication that price is to be
fixed at time of exercise

N/A


22. Total number of shares or debentures over which options held following this
notification

N/A


23. Any additional information




24. Name of contact and telephone number for queries

MICHAEL ANSCOMBE
TEL: 01293 767676


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

MICHAEL ANSCOMBE


Date of Notification

25 FEBRUARY 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 25 February 2005                          By   ____/s/ Luke Thomas____

                                                    (Signature)*