SIP Operation

National Grid PLC
11 August 2005


National Grid plc (NG.)
11 August 2005

SHARE INCENTIVE PLAN (the 'SIP')- August 2005 Operation

(Notification of Directors' Interests, pursuant to Section 324(2)
of the Companies Act 1985)

----------------------------------------------------------------

Under the SIP scheme, operated through Towers Perrin Share Plan Services Limited
as Trustee, employees may acquire NG ordinary shares by regular monthly
contributions. The current monthly purchase of 49,255 NG ordinary shares under
the scheme was confirmed by the Trustee, the shares having been purchased in the
market on Tuesday 9th August 2005, at a price of 520 pence per share, on behalf
of some 2,800 participants.

The following Executive Directors are beneficiaries of the number of shares
purchased on their behalf:

Director                                      Shares purchased in SIP

Steven Holliday                                          25
Roger Urwin                                              25


                      This information is provided by RNS
            The company news service from the London Stock Exchange