Rule 8.1- O2 plc

Telefonica SA
07 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                               02 plc

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

Date of dealing                                06 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                        399,603,515*         (4.56%)


(2) Derivatives (other than options)


(3) Options and agreements to purchase/sell


Total                                          399,603,515*          (4.56%)



*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                               64,575,674                            GBP 1.9599




(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                                     07 December 2005

Contact name                                           Nicholas Child - Senior Compliance Officer -
                                                       Citigroup Global Markets Limited


Telephone number                                       [phone]

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



                                                             SUPPLEMENTAL FORM 8



                           DETAILS OF OPEN POSITIONS

   (This form should be attached to Form 8.1, Form 8.1(b)(ii) or Form 8.3, as
                                  appropriate)



OPEN POSITIONS (Note 1)


Product name,        Written or      Number of securities   Exercise price   Type, e.g.     Expiry date
                     purchased       to which the option or (Note 2)         American,
e.g. call option                     derivative relates                      European etc.





Notes



1. Where there are open option positions or open derivative positions (except
for CFDs), full details should be given.  Full details of any  existing
agreements to purchase or to sell  should also be given on this form.



2. For all prices and other monetary amounts, the currency must be stated.



For details of the Code's dealing disclosure requirements, see Rule 8 and its
Notes which can be viewed on the Takeover Panel's website at
www.thetakeoverpanel.org.uk





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