National Grid PLC — Capital/Financing Update 2022

May 19, 2022

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 16 August 2021 (as supplemented by the first supplement to the prospectus dated 18 November 2021 (together, the "Prospectus")), which comprises a base prospectus for each of National Grid plc ("National Grid") and National Grid Electricity Transmission plc ("NGET" and, together with National Grid, the "Issuers"), constitutes a supplementary prospectus for the purposes of the UK 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. When used in this Supplement, "UK Prospectus Regulation" means Regulation (EU) 2017/1129 as it forms part of United Kingdom domestic law by virtue of the European Union (Withdrawal) Act 2018.

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 its import.

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. To the extent that any document or information incorporated by reference or attached to this Supplement itself incorporates any information by reference, either expressly or impliedly, such information will not form part of this Supplement for the purposes of the UK Prospectus Regulation and the Listing Rules except where such information or documents are stated within this Supplement as being specifically incorporated by reference or where this Supplement is specifically defined as including such information.

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 2022 (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 2022

On 19 May 2022, National Grid published its Preliminary Results for the year ended 31 March 2022 (https://www.nationalgrid.com/document/146546/download).

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………………………………………………………55-56
Consolidated statement of comprehensive income…………………………………57
Consolidated statement of changes in equity………………………………………58
Consolidated statement of financial position…………………………………………59
Consolidated cash flow statement…………………………………………………….60
Notes to the consolidated financial statements………………………………………61-90
Alternative performance measures/non-IFRS reconciliations………………………91-106

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 155 of the Prospectus, there has been no significant change in the financial performance or financial position of National Grid or the National Grid Group since 31 March 2022.

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.