FORM 6-K

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                        Report of Foreign Private Issuer


                        Pursuant to Rule 13a-16 or 15d-16
                     of the Securities Exchange Act of 1934


                                 12 APRIL 2005


                                    O2 plc


                                Wellington Street
                       Slough, Berkshire SL1 1YP, England

                    (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 ________


Enclosure:

Copy of announcement regarding Director Declaration sent to the
London Stock Exchange on 12 April 2005





 KATHLEEN O'DONOVAN - DISCLOSURE OF DIRECTOR DETAILS


O2 plc announced on 30 March 2005 that Kathleen O'Donovan was appointed to the
O2 plc Board as an additional Non- Executive Director.

The following notification is provided as per Paragraphs 16.4 and 16.5 of
Chapter 16 of the UKLA Listing Rules and the obligation to notify Directors
share interests.

16.4 (a)      Other Directorships of publicly quoted companies.

              Ms O'Donovan is a Director of EMI Group plc.
              Ms O'Donovan is a Director of Prudential plc.
              Ms O'Donovan is a Director of Great Portland Estates plc.
              Ms O'Donovan was previously a Director of Invensys plc (1991-2003)
16.4 (b)      None


Should you require any further information please contact:

Robert Harwood
Assistant Secretary
O2 plc

Telephone: 01753 628200


                              SIGNATURE

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.



                                                 O2 plc


Date: 12 April 2005                        By:___/s/ Robert Harwood___

                                           ROBERT HARWOOD
                                           Assistant Secretary