Washington D.C. 20549

Commission file number: 001-14958

1-3 Strand London,England WC2N 5EH

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F þ                     Form 40-F o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): o

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3- 2(b) under the Securities Exchange Act of 1934. Yes  o                No  þ

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b):

THIS REPORT ON FORM 6-K SHALL BE DEEMED TO BE INCORPORATED BY REFERENCE IN EACH OF THE REGISTRATION STATEMENTS ON FORM F-3 (FILE NO. 333-160013) AND ON FORM S-8 (FILE NO.S 333-170716, 333-175852, 333-155527, 333-149828, 333-107727, 333-103768, 333-97249, 333-65968, AND 333-33094) OF NATIONAL GRID PLC AND TO BE A PART THEREOF FROM THE DATE ON WHICH THIS REPORT IS FURNISHED, TO THE EXTENT NOT SUPERSEDED BY DOCUMENTS OR REPORTS SUBSEQUENTLY FILED OR FURNISHED.

 

 

 

Please see Exhibit 99.1 Announcement sent to the London Stock Exchange on 17 November 2011 — ‘National Grid plc Half year report for the six months ended 30 September 2011 (unaudited)’

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorised.

Date: 17 November 2011

EXHIBIT INDEX