National Grid Regulatory News (NG.)

1a. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attachedii:

National Grid PLC

1b. Please indicate if the issuer is a non-UK issuer (please mark with an "X" if appropriate)

Non-UK issuer

2. Reason for the notification (please mark the appropriate box or boxes with an "X")

An acquisition or disposal of voting rights

X

An acquisition or disposal of financial instruments

An event changing the breakdown of voting rights

Other (please specify)iii:

3. Details of person subject to the notification obligationiv

Name

BlackRock, Inc.

City and country of registered office (if applicable)

Wilmington, DE, USA

4. Full name of shareholder(s) (if different from 3.)v

Name

City and country of registered office (if applicable)

5. Date on which the threshold was crossed or reachedvi:

17/11/2017

6. Date on which issuer notified (DD/MM/YYYY):

20/11/2017

7. Total positions of person(s) subject to the notification obligation

% of voting rights attached to shares (total of 8. A)

% of voting rights through financial instruments(total of 8.B 1 + 8.B 2)

Total of both in % (8.A + 8.B)

Total number of voting rights of issuervii

Resulting situation on the date on which threshold was crossed or reached

3.60%

3.06%

6.67%

3,397,361,362

Position of previous notification (if

applicable)

5.89%

0.39%

6.29%

8. Notified details of the resulting situation on the date on which the threshold was crossed or reachedviii

A: Voting rights attached to shares

Class/type ofshares

ISIN code (if possible)

Number of voting rightsix

% of voting rights

Direct

(Art 9 of Directive 2004/109/EC) (DTR5.1)

Indirect

(Art 10 of Directive 2004/109/EC) (DTR5.2.1)

Direct

(Art 9 of Directive 2004/109/EC) (DTR5.1)

Indirect

(Art 10 of Directive 2004/109/EC) (DTR5.2.1)

GB00BDR05C01

122,594,750

3.60%

SUBTOTAL 8. A

122,594,750

3.60%

B 1: Financial Instruments according to Art. 13(1)(a) of Directive 2004/109/EC (DTR5.3.1.1 (a))

Type of financial instrument

Expirationdatex

Exercise/Conversion Periodxi

Number of voting rights that may be acquired if the instrument is

exercised/converted.

% of voting rights

Securities Lending

102,357,208

3.01%

American Depository Receipt

1,000

0.00%

SUBTOTAL 8. B 1

102,358,208

3.01%

B 2: Financial Instruments with similar economic effect according to Art. 13(1)(b) of Directive 2004/109/EC (DTR5.3.1.1 (b))

Type of financial instrument

Expirationdatex

Exercise/Conversion Period xi

Physical or cash

settlementxii

Number of voting rights

% of voting rights

CFD

Cash

1,859,724

0.05%

SUBTOTAL 8.B.2

1,859,724

0.05%

9. Information in relation to the person subject to the notification obligation (please mark the

applicable box with an "X")

Person subject to the notification obligation is not controlled by any natural person or legal entity and does not control any other undertaking(s) holding directly or indirectly an interest in the (underlying) issuerxiii

Full chain of controlled undertakings through which the voting rights and/or thefinancial instruments are effectively held starting with the ultimate controlling natural person or legal entityxiv (please add additional rows as necessary)

X

Namexv

% of voting rights if it equals or is higher than the notifiable threshold

% of voting rights through financial instruments if it equals or is higher than the notifiable threshold

Total of both if it equals or is higher than the notifiable threshold

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock Group Limited

BlackRock Advisors (UK) Limited

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock Holdco 4, LLC

BlackRock Holdco 6, LLC

BlackRock Delaware Holdings Inc.

BlackRock Fund Advisors

BlackRock Institutional Trust Company, National Association

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock Group Limited

BlackRock Investment Management (UK) Limited

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock (Singapore) Holdco Pte. Ltd.

BlackRock Asia-Pac Holdco, LLC

BlackRock HK Holdco Limited

BlackRock Cayco Limited

BlackRock Trident Holding Company Limited

BlackRock Japan Holdings GK

BlackRock Japan Co., Ltd.

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock Holdco 4, LLC

BlackRock Holdco 6, LLC

BlackRock Delaware Holdings Inc.

BlackRock Fund Advisors

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock Australia Holdco Pty. Ltd.

BlackRock Investment Management (Australia) Limited

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock Capital Holdings, Inc.

BlackRock Advisors, LLC

BlackRock, Inc.

Trident Merger, LLC

BlackRock Investment Management, LLC

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock Group Limited

BlackRock International Limited

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock Holdco 3, LLC

BlackRock Canada Holdings LP

BlackRock Canada Holdings ULC

BlackRock Asset Management Canada Limited

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock Group Limited

BlackRock Investment Management (UK) Limited

BlackRock Asset Management Deutschland AG

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock (Singapore) Holdco Pte. Ltd.

BlackRock (Singapore) Limited

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock (Singapore) Holdco Pte. Ltd.

BlackRock Asia-Pac Holdco, LLC

BlackRock HK Holdco Limited

BlackRock Asset Management North Asia Limited

BlackRock, Inc.

BlackRock Holdco 2, Inc.

BlackRock Financial Management, Inc.

BlackRock International Holdings, Inc.

BR Jersey International Holdings L.P.

BlackRock Group Limited

BlackRock (Netherlands) B.V.

10. In case of proxy voting, please identify:

Name of the proxy holder

The number and % of voting rights held

The date until which the voting rights will be held

11. Additional informationxvi

BlackRock Regulatory Threshold Reporting Team Jana Blumenstein

020 7743 3650

Place of completion

12 Throgmorton Avenue, London, EC2N 2DL, U.K.

Date of completion

20 November, 2017