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 October 2004 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 BARCLAYS PLC 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 NAMED 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 BANK OF NEW YORK 214075 3,861,569 BANK OF NEW YORK 221428 524,342 BANK OF NEW YORK 367748 2,596,205 BANK OF NEW YORK 392067 3,952,562 BANK OF NEW YORK 392177 313,638 BARCLAYS CAPITAL NOMINEES LIMI 754,502 BNY (OCS) NOMINEES LTD 221476 252,149 BNY (OCS) NOMINEES LTD 387173 123,795 BOISS NOMINEES LTD 4224361 394,969 CHASE NOMINEES LTD 16376 531,812 CHASE NOMINEES LTD 16649 41,844 CHASE NOMINEES LTD 16669 63,310 CHASE NOMINEES LTD 18243 123,823 CHASE NOMINEES LTD 19518 253,833 CHASE NOMINEES LTD 19519 2,464,292 CHASE NOMINEES LTD 19520 638,744 CHASE NOMINEES LTD 20947 36,769,332 CHASE NOMINEES LTD 21359 1,220,660 CHASE NOMINEES LTD 25772 520,077 CHASE NOMINEES LTD 27793 74,767 CHASE NOMINEES LTD 27795 114,340 CHASE NOMINEES LTD 27797 138,568 CHASE NOMINEES LTD 27799 299,495 CHASE NOMINEES LTD 27800 1,145,581 CHASE NOMINEES LTD 27802 40,008 CHASE NOMINEES LTD 28269 106,605 CHASE NOMINEES LTD 28270 590,971 CHASE NOMINEES LTD 28270 266,132 CHASE NOMINEES LTD 31961 1,347,971 CIBC MELLON GLOBAL SECURITIES 34,666 CITIBANK 6010613363 333,841 CITIBANK 6010640794 252,237 CITIBANK 6010782807 275,601 DEUTSCHE (BANKERS TRUST) 501575013 378,406 DEUTSCHE BANK LONDON 8003168 30,331 HSBC 813168 808,840 HSBC 814537 80,198 HSBC 845315 23,453 INVESTORS BANK AND TRUST CO 314,881 INVESTORS BANK AND TRUST CO 841,643 INVESTORS BANK AND TRUST CO 2,914,583 INVESTORS BANK AND TRUST CO 10,802 INVESTORS BANK AND TRUST CO 349,682 INVESTORS BANK AND TRUST CO 111,024 JP MORGAN (BGI CUSTODY) 16331 268,799 JP MORGAN (BGI CUSTODY) 16341 667,949 JP MORGAN (BGI CUSTODY) 16341 1,754,917 JP MORGAN (BGI CUSTODY) 16344 400,264 JP MORGAN (BGI CUSTODY) 16345 742,167 JP MORGAN (BGI CUSTODY) 16400 8,915,859 JP MORGAN (BGI CUSTODY) 16612 154,621 JP MORGAN (BGI CUSTODY) 16621 186,353 JP MORGAN (BGI CUSTODY) 16644 420,978 JP MORGAN (BGI CUSTODY) 16901 127,521 JP MORGAN (BGI CUSTODY) 18409 526,737 JP MORGAN (BGI CUSTODY) 19514 128,618 JP MORGAN (BGI CUSTODY) 27795 258,537 JP MORGAN (BGI CUSTODY) 27799 785,257 JP MORGAN (BGI CUSTODY) 28166 3,027,976 JP MORGAN (BGI CUSTODY) 29514 117,527 JPM FRANKFURT 27717 67,625 JP MORGAN CHASE BANK 360,275 JP MORGAN CHASE BANK 381,288 JP MORGAN CHASE BANK 479,984 JP MORGAN CHASE BANK 6,566 JP MORGAN CHASE BANK 188,365 MELLON BANK ABGFZ872482 745,728 MELLON BANK TGGF0003002 91,742 MELLON TRUST - BOSTON & SF 128,392 MELLON TRUST OF NEW ENGLAND 193,162 MIDLAND BANK (HSBC BANK PLC) 772823 1,951,762 NORTHERN TRUST CVS21 987,313 NORTHERN TRUST LIV02 746,036 NORTHERN TRUST SCO06 303,975 NORTHERN TRUST TNF01 384,795 NORTHERN TRUST USF06 193,023 NORTHERN TRUST USF12 1,760,355 NORTHERN TRUST BANK - BGI SEPA 168,498 NORTHERN TRUST BANK - BGI SEPA 41,732 NORTHERN TRUST BANK - BGI SEPA 256,471 R C GREIG NOMINEES LIMITED A/C BL1 140,823 R C GREIG NOMINEES LIMITED A/C CM1 32,079 R C GREIG NOMINEES LIMITED GP1 GP1 34,067 R C GREIG NOMINEES LIMITED SA1 SA1 22,152 STATE STREET 2RJ2 127,458 STATE STREET JD12 447,165 STATE STREET N3B2 8,621 STATE STREET N3B6 273,550 STATE STREET N3YZ 10,446 STATE STREET VE4J 205,686 VIDACOS NOMINEES LIMITED 6010830763 1,800,140 ZEBAN NOMINEES LIMITED 21,700 ZEBAN NOMINEES LIMITED 1,000 TOTAL 97,332,138 5. Number of shares / amount of stock acquired - 6. Percentage of issued class - 7. Number of shares / amount of stock disposed NOT NOTIFIED 8. Percentage of issued class NOT NOTIFIED 9. Class of security ORDINARY SHARES OF 3.3333 PENCE EACH 10. Date of transaction HOLDING AS AT 28 SEPTEMBER 2004 11. Date company informed 01 OCTOBER 2004 12. Total holding following this notification 97,332,138 13. Total percentage holding of issued class following this notification 10.20% 14. Any additional information NOTIFICATION RECEIVED PURSUANT TO S198-202 COMPANIES ACT 1985 THAT THE SHAREHOLDER NAMED IN 2 ABOVE HAS DECREASED THEIR SHAREHOLDING IN SPIRENT PLC TO 10.20%. SHAREHOLDER PREVIOUSLY REPORTED A SHAREHOLDING OF 105,945,146 SHARES (11.17%) ON 12 MARCH 2004. 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 01 OCTOBER 2004 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 01 October 2004 By ____/s/ Luke Thomas____ (Signature)*