National Grid PLC — Capital/Financing Update 2020

Jun 18, 2020

National Grid plc

(incorporated with limited liability in England and Wales on 11 July 2000 under registered number 4031152)

National Grid Electricity Transmission plc

(incorporated with limited liability in England and Wales on 1 April 1989 under registered number 2366977)

Euro 15,000,000,000 Euro Medium Term Note Programme

This supplement (the "Supplement") to the prospectus dated 30 July 2019 (as supplemented by the first supplement to the prospectus dated 21 November 2019 and the second supplement to the prospectus dated 7 April 2020 (together, the "Prospectus")), which comprises a base prospectus for each of National Grid plc ("National Grid") and National Grid Electricity Transmission plc (together, the "Issuers"), constitutes a supplementary prospectus for the purposes of the Prospectus Regulation and supplementary listing particulars for the purposes of Section 81 of FSMA. This Supplement is prepared in connection with the Euro 15,000,000,000 Euro Medium Term Note Programme established by the Issuers. Terms defined in the Prospectus have the same meaning when used in this Supplement.

This Supplement is supplemental to, and should be read in conjunction with, the Prospectus and any other supplements to the Prospectus issued by the Issuers.

Each of the Issuers accepts responsibility for the information contained in this Supplement. To the best of the knowledge of each Issuer the information contained in this Supplement is in accordance with the facts and this Supplement makes no omission likely to affect the import of such information.

To the extent that there is any inconsistency between (a) any statement in this Supplement or any statement incorporated by reference into the Prospectus by this Supplement and (b) any other statement in, or incorporated by reference in, the Prospectus, the statements in this Supplement will prevail.

The Prospectus, this Supplement and the documents incorporated by reference in the Prospectus can be viewed on the website of the Regulatory News Service operated by the London Stock Exchange plc at www.londonstockexchange.com/exchange/news/market-news/market-news-home.html. If documents which are incorporated by reference themselves incorporate any information or other documents therein, such information or other documents will not form part of this Supplement for the purposes of the Prospectus Regulation and the Listing Rules except where such information or other documents are stated within this Supplement as being specifically incorporated by reference in to this Supplement.

Purpose of this Supplement

The purpose of this Supplement is to (i) incorporate by reference the preliminary unaudited annual results of National Grid for the financial year ended 31 March 2020 (the "Preliminary Results") in the Prospectus; and (ii) amend the no significant change statement in paragraph 10 of the "General Information" section of the Prospectus.

Incorporation of the Preliminary Results for the year ended 31 March 2020

On 18 June 2020, National Grid published Preliminary Results.

A copy of the Preliminary Results has been filed with the Financial Conduct Authority and, by virtue of this Supplement, the parts of the Preliminary Results denoted by these page number references are incorporated by reference herein:

Consolidated income statement .............................................................................40-41

Consolidated statement of comprehensive income42
Consolidated statement of changes in equity43
Consolidated statement of financial position 44
Consolidated cash flow statement45
Notes to the consolidated financial statements 46-71
Alternative Performance Measures/Non-IFRS Reconciliations 72-83

The financial information contained in the Preliminary Results has been properly prepared on the basis stated therein and in a manner consistent with the accounting policies of National Grid and, except as disclosed in Note 1 of the Notes to the Consolidated Financial Statements in the Preliminary Results, on a basis comparable with the historical financial information of National Grid.

No Significant Change Statement

As a result of the publication of the Preliminary Results and further to the statement made in paragraph 10 of the section headed "General Information" on page 140 of the Prospectus, there has been no significant change in the financial performance or position of National Grid or the National Grid Group since 31 March 2020.

General Information

Copies of all documents incorporated by reference in the Prospectus will be available on the website of National Grid, as set out in the Prospectus.

Save as disclosed in this Supplement, no significant new factor, material mistake or material inaccuracy relating to information included in the Prospectus has arisen or been noted, as the case may be, in relation to either of the Issuers since the publication of the Prospectus.