Rule 8.1- O2 plc

Telefonica SA
02 December 2005


                                                                        FORM 8.1

          DEALINGS BY OFFERORS, OFFEREE COMPANIES OR THEIR ASSOCIATES

                  FOR THEMSELVES OR FOR DISCRETIONARY CLIENTS

      (Rules 8.1(a) and (b)(i) of the City Code on Takeovers and Mergers)



1.         KEY INFORMATION


Name of person dealing (Note 1)               Telefonica, S.A.

Company dealt in                              O2 plc

Class of relevant security to which the       Ordinary Shares
dealings being disclosed relate (Note 2)

Date of dealing                               01 December 2005


2.            INTERESTS, SHORT POSITIONS AND RIGHTS TO SUBSCRIBE



(a)            Interests and short positions (following dealing) in the class of
relevant security dealt in (Note 3)


                                                            Long                               Short


                                              Number                            Number
                                                        (%)                                 (%)

(1) Relevant securities                       237,200,770* 2.70 %                                                (    )

(2) Derivatives (other than options)

(3) Options and agreements to purchase/sell

Total                                         237,200,770* 2.70 %



*This includes 14,422 shares held by Casiopea Reaseguradora, S.A., a subsidiary
 of Telefonica, S.A. and deemed to be acting in concert with Telefonica, S.A.,
 purchased prior to the commencement of the Offer Period.

(b)            Interests and short positions in relevant securities of the
company, other than the class dealt in (Note 3)


Class of relevant security:                                 Long                              Short
                                              Number                           Number
                                                         (%)                              (%)

(1) Relevant securities


(2) Derivatives (other than options)


(3) Options and agreements to purchase/sell


Total




(c)        Rights to subscribe (Note 3)


Class of relevant security:                   Details



3.            DEALINGS (Note 4)



(a)            Purchases and sales


Purchase/sale                          Number of securities                 Price per unit (Note 5)


Purchase                               43,000,000                           196.10


Purchase                               8,710,117                            196.05


Purchase                               18,289,883                           196.05




(b)            Derivatives transactions (other than options)


Product name,         Long/short (Note 6)       Number of securities (Note 7)       Price per unit (Note 5)
e.g. CFD







(c)            Options transactions in respect of existing securities

(i)            Writing, selling, purchasing or varying


Product name,        Writing, selling, Number of securities Exercise   Type, e.g.     Expiry     Option money
                       purchasing,     to which the option             American,
e.g. call option     varying etc.      relates (Note 7)     price      European etc.  date       paid/received
                                                                                                 per unit (Note
                                                                                                 5)




(ii)            Exercising


Product name, e.g. call option         Number of securities                 Exercise price per unit (Note 5)





(d)        Other dealings (including new securities) (Note 4)


Nature of transaction (Note 8)         Details                              Price per unit (if applicable) (Note 5)




4.            OTHER INFORMATION



Agreements, arrangements or understandings relating to options or derivatives



Full details of any agreement, arrangement or understanding between the person disclosing and any other person relating
to the voting rights of any relevant securities under any option referred to on this form or relating to the voting
rights or future acquisition or disposal of any relevant securities to which any derivative referred to on this form is
referenced.  If none, this should be stated.





Is a Supplemental Form 8 attached? (Note 9)                       NO


Date of disclosure                                                02 December 2005

Contact name                                                      Nicholas Child

                                                                  Senior Compliance Officer - Citigroup Global
                                                                  Markets Limited
Telephone number                                                  + 44 207 508 68 21


Name of offeree/offeror with which associated                     Telefonica, S.A.

Specify category and nature of associate status (Note 10)         N/A



Notes



The Notes on Form 8.1 can be viewed on the Takeover Panel's website at
www.thetakeoverpanel.org.uk



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