Rule 2.10 Announcement

Rule 2.10 Announcement

Centrica PLC

15 December 2008

Disclosure in accordance with Rule 2.10 of the City Code

In accordance with Rule 2.10 of the City Code on Takeovers and Mergers, Centrica plc (the “Company”) confirms that at the close of business on 12 December 2008, it had 3,714,157,509 ordinary shares of 6 14/81p each in issue.

Following completion of the rights issue announced by the Company on 31 October 2008, the Company will have 5,106,946,682 ordinary shares of 6 14/81p each in issue.

As announced on 21 November 2008, any person who is interested in 1% or more of any class of the Company’s relevant securities at midnight today, or who was so interested at midnight on 12 December, and who in either case either (i) dealt in entitlements to New Shares under the Rights Issue (whether nil paid or fully paid) at any time or (ii) subscribed for all or part of their entitlements under the Rights Issue, must disclose their aggregate interests, rights to subscribe and short positions in the Company’s relevant securities by no later than 3.30pm tomorrow.

The ISIN reference for the shares is GB00B033F229.

Enquiries:

Centrica Investor Relations: 01753 494900

Centrica Media Relations: 0845 072 8001