Rule 8.3 - O2 PLC

FORM 8.3

    DEALINGS BY PERSONS WITH INTERESTS IN SECURITIES REPRESENTING 1% OR MORE
              (Rule 8.3 of the City Code on Takeovers and Mergers)


1.   KEY INFORMATION

Name of person dealing        BARCLAYS PLC
(Note 1)
Company dealt in              O2 PLC
Class of relevant security    ORD GBP 0.001
to which the dealings being
disclosed relate (Note 2)
Date of dealing               09 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    269,485,951   (3.07%)              0   (0.00%)
securities
(2) Derivatives           0   (0.00%)        779,144   (0.01%)
(other than
options)
(3) Options and   1,001,400   (0.01%)      2,000,600   (0.02%)
agreements to
purchase/sell
Total           270,487,351   (3.08%)      2,779,744   (0.03%)




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

Class of                    Long                     Short
relevant
security:

                  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
                                   (GBP)
Purchase      286,047              1.9657
Purchase      83,987               1.9725
Purchase      7,257                1.9700
Purchase      160,000              1.9646
Purchase      371,355              1.9725
Sale          347,390              1.9725
Sale          21,382               1.9625
Sale          1,065                1.9626
Sale          770                  1.9626
Sale          940                  1.9626
Sale          3,668                1.9679



(b)  Derivatives transactions (other than options)

Product    Long/Short    Number of Securities  Price Per
name,      (Note 6)      (Note 7)              Unit (GBP)
e.g. CFD




(c)  Options transactions in respect of existing securities

(i)  Writing, selling, purchasing or varying

Product   Writing,    Number of    Exerc Type,     Expir  Option
name,     selling,    securities   ise   e.g.      y      money
e.g. call purchasing  to which     price American  date   paid/recei
option    , varying   the option         ,                ved per
          etc.        relates            European         unit (GBP)
                      (Note 7)           etc.


(ii) Exercising

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



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


Nature of transaction Details           Price per unit
(Note 8)                                (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                         12 DECEMBER 2005
Contact name                               BARCLAYS CORPORATE SECRETARIAT
Telephone number                           020 7116 2913
If a connected EFM, name of
offeree/offeror with which connected
If a connected EFM, state nature of
connection (Note 10)


Notes

The Notes on Form 8.3 can be viewed on the Takeover Panel's website at
www.thetakeoverpanel.org.uk