##### Table of Contents





SECURITIES AND EXCHANGE
    COMMISSIONWashington, D.C.
    20549
 FORM 20-F
 (Mark One)o

REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR(g) OF THE
    SECURITIES EXCHANGE ACT OF 1934ORþ

ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
    SECURITIES EXCHANGE ACT OF 1934For the fiscal year ended 31 March 2010ORo

TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
    SECURITIES EXCHANGE ACT OF 1934ORo

SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
    SECURITIES EXCHANGE ACT OF 1934Date of event requiring this
    shell company
    reportFor the transition period
    from  to   Commission file number:
    001-14958
  NATIONAL GRID PLC
 (Exact name of Registrant as
    specified in its charter)
  England and Wales
 (Jurisdiction of incorporation
    or organization)
  1-3 Strand, London WC2N 5EH,
    England
 (Address of principal executive
    offices)
  Helen Mahy
 011 44 20 7004 3000
 Facsimile No. 011 44 20
    7004 3004
 Company Secretary and General
    Counsel
 National Grid plc
 1-3 Strand London WC2N 5EH,
    England
 (Name, Telephone,
    E-mail
    and/or Facsimile number and Address of Company Contact
    Person)
  Securities registered or to be registered pursuant to
    Section 12(b) of the Securities Exchange Act of 1934:
  Title of each class

Name of each exchange on which registeredOrdinary Shares of
    1117/43
    pence each

The New York Stock Exchange*American Depositary Shares, each representing five

The New York Stock ExchangeOrdinary Shares of
    1117/43
    pence each6.625% Guaranteed Notes due 2018

The New York Stock Exchange6.30% Guaranteed Notes due 2016

The New York Stock ExchangePreferred Stock ($100 par value-cumulative):3.90% Series

The New York Stock Exchange3.60% Series

The New York Stock Exchange     *
    
    Not for trading, but only in
    connection with the registration of American Depositary Shares
    representing Ordinary Shares pursuant to the requirements of the
    Securities and Exchange Commission.  Securities registered or to be registered pursuant to
    Section 12(g) of the Securities Exchange Act of 1934:
  Securities for which there is a reporting obligation pursuant
    to Section 15(d) of the Securities Exchange Act of 1934:
    Ordinary Shares of
    1117/43
    pence each

2,617,190,095   þ o
  o þ
    þ o
  Regulation S-T o o
  Rule 12b-2
  Large accelerated filer þ

Accelerated filer o

Non-accelerated filero     o þ o
  o o
  Rule 12b-2 o þ




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##### Table of Contents





Cautionary
    Statement
  Form 20-F non-network
   i




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##### 



TABLE OF
    CONTENTS
  
  PART IItem 1.

Identity of Directors, Senior Management and
    Advisers

1Item 2.

Offer Statistics and Expected Timetable

1Item 3.

Key Information

1Item 4.

Information on the Company

3Item 4A.

Unresolved Staff Comments

5Item 5.

Operating and Financial Review and Prospects

5Item 6.

Directors, Senior Management and Employees

5Item 7.

Major Shareholders and Related Party
    Transactions

5Item 8.

Financial Information

6Item 9.

The Offer and Listing

6Item 10.

Additional Information

7Item 11.

Quantitative and Qualitative Disclosures about
    Market Risk

12Item 12.

Description of Securities Other than Equity
    Securities

13PART IIItem 13.

Defaults, Dividend Arrearages and
    Delinquencies

14Item 14.

Material Modifications to the Rights of Security
    Holders and Use of Proceeds

14Item 15.

Controls and Procedures

14Item 16.

[Reserved]

15Item 16A.

Audit Committee Financial Expert

15Item 16B.

Code of Ethics

15Item 16C.

Principal Accountant Fees and Services

15Item 16D.

Exemptions from the Listing Standards for Audit
    Committees

16Item 16E.

Purchases of Equity Securities by the Issuer and
    Affiliated Purchasers

16Item 16F.

Change in Registrants Certifying
    Accountant

16Item 16G.

Corporate Governance

16PART IIIItem 17.

Financial Statements

16Item 18.

Financial Statements

16Item 19.

Exhibits

18SIGNATURE

23EX-1.1EX-2.B.11.1EX-2.B.12.1EX-2.B.13.1EX-4.A.1Ex-8EX-12.1EX-12.2EX-13EX-15.1EX-15.2   ii




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##### Table of Contents



PART I  Item 1.
    Identity
    of Directors, Senior Management and Advisers    Item 2.
    Offer
    Statistics and Expected Timetable    Item 3.
    Key
    Information    Selected
    financial data
  Amounts
    in accordance with
    IFRS1:
  2010

2009

2008

2007

2006Revenue

£m


13,988



15,624



11,423



8,695



8,868Total operating profit

£m


3,293



2,623



2,964



2,513



2,374Profit for the year from continuing operations

£m


1,389



922



1,575



1,310



1,183Profit for the year

£m


1,389



947



3,193



1,396



3,850Basic earnings per share from continuing
    operations2

Pence


56.1



36.9



59.5



47.4



41.1Diluted earnings per share from continuing operations

Pence


55.8



36.6



59.1



47.2



40.9Basic earnings per share

Pence


56.1



37.9



120.7



50.6



134.0Diluted earnings per share

Pence


55.8



37.6



120.0



50.3



133.3Number of shares  basic

Millions


2,470



2,490



2,644



2,754



2,872Number of shares  diluted

Millions


2,483



2,507



2,659



2,772



2,886Total assets

£m


43,553



44,467



37,771



28,389



25,924Net assets

£m


4,211



3,984



5,374



4,136



3,493Total parent company shareholders equity

£m


4,199



3,970



5,356



4,125



3,482Dividends per ordinary share: paid during the year

Pence


36.65



33.94



29.5



26.8



25.4Dividends per ordinary share: approved or proposed during the
    year

Pence


38.49



35.64



33.0



28.7



26.1Dividends per ordinary share: paid during the year

US

$
0.579



0.523



0.593



0.513



0.455Dividends per ordinary share: approved or proposed during the
    year

US

$
0.608



0.549



0.663



0.549



0.467     (1)

    
    Since the implementation of IFRS by the Company, there have been
    no significant changes in accounting standards, interpretations
    or policies that have had a material financial impact on the
    selected financial data. 1




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The selected financial data incorporates businesses acquired in
    the period from the date of their acquisitions, principally
    KeySpan Corporation acquired in August 2007 and our Rhode Island
    gas distribution operations acquired in August 2006.
    Comparatives for 2008 have been restated for the finalization of
    the fair value exercise on the acquisition of KeySpan
    Corporation.The selected financial data for continuing operations excludes
    businesses discontinued during the periods presented,
    principally our Ravenswood generation station, disposed of in
    August 2008, our former UK and US wireless operations and our
    former electricity interconnector business in Australia,
    disposed of in April and August 2007 and four gas distribution
    networks in the UK disposed of in June 2005.(2)

    
    In accordance with IAS 33, per share data for comparative
    periods has been restated as a result of shares issued via scrip
    dividends.  Dividends
    Exchange
    Rates
    High

LowMay 2010*


1.5116



1.4305April 2010


1.5499



1.5200March 2010


1.5295



1.4885February 2010


1.5969



1.5224January 2010


1.6372



1.5935December 2009


1.6658



1.5932November 2009


1.6796



1.6379   Average**2009/10


1.582008/09


1.542007/08


2.012006/07


1.912005/06


1.78     *
    
    For the period to 21 May 2010.**
    
    The average for each period is calculated by using the average
    of the exchange rates on the last day of each month during the
    period.  Risk
    factors
   2




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Item 4.
    Information
    on the Company  History
    and development of the Company
      Business
    overview
    Organizational
    structure
    Property,
    plant and equipment
  United
    Kingdom
  15-year 20-year
  UK electricity and gas transmission.
     3




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UK gas distribution.
    United
    States
      US electricity transmission. sub-transmission right-of-way sub-transmission Right-of-way sub-transmission
  US electricity and gas distribution. rights-of-way
 4




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rights-of-way Right-of-way
    Item 4A.
    Unresolved
    Staff Comments    Item 5.
    Operating
    and Financial Review and Prospects    Item 6.
    Directors,
    Senior Management and Employees      Item 7.
    Major
    Shareholders and Related Party Transactions  Major
    shareholders
    Number of

% of OutstandingOrdinary Shares

Share Capital*Black Rock Inc.


123,761,405



4.99Legal and General Group plc


107,703,278



4.35Crescent Holding GmbH


106,724,490



4.34Capital Group Companies, Inc.


102,067,366



3.75FMR Corp.


82,805,863



3.06     *
    
    This number is calculated in relation to the issued share
    capital at the time the holding was disclosed.     5




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Item 8.
    Financial
    Information    Item 9.
    The
    Offer and Listing  Price
    history
    Ordinary Share(Pence)

ADS ($)High

Low

High

Low2009/10


685.50



511.00



56.59



38.252008/09


754.00



515.00



74.89



36.642007/08


863.00



686.00



86.58



69.222006/07


797.50



552.00



78.81



48.832005/06


613.50



489.25



53.45



44.482004/05


549.50



421.25



52.06



37.592009/10 Q4


685.50



619.50



55.13



46.85Q3


683.50



572.50



56.59



46.13Q2


628.00



529.50



52.00



43.05Q1


617.00



511.00



50.25



38.252008/09 Q4


717.00



515.00



53.57



36.64Q3


748.50



531.50



65.42



43.40Q2


737.00



639.60



69.74



60.58Q1


754.00



638.50



74.89



63.74May 2010*


638.00



551.50



48.79



40.00April 2010


666.00



626.00



51.00



47.76March 2010


665.00



628.50



50.18



46.85February 2010


653.50



619.50



51.60



48.38January 2010


685.50



628.00



55.13



49.95December 2009


683.50



636.50



56.03



52.09     *
    
    For the period to 21 May 2010. 6




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Markets
    Item 10.
    Additional
    Information  Articles
    of Association
      General
    Directors
          Rights,
    Preferences and Restrictions
  called-up
     7




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winding-up,
  Variation
    of Rights
    General
    Meetings
    Rights
    of Non-Residents
    Disclosure
    of Interests
     8




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Material
    contracts
      Underwriting
    Agreement
      Exchange
    controls
  and/or
 9




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Taxation
      
    the beneficial owner of the ADSs or ordinary shares, as
    applicable, and of any dividends that you receive;
    an individual resident or citizen of the US, a
    US corporation, or a US partnership, estate, or trust (but
    only to the extent the income of the partnership, estate, or
    trust is subject to US taxation in the hands of a US resident
    person); and
    not also a resident of the UK for UK tax purposes.    mark-to-market
    A US Holder should consult its own adviser as to the tax
    consequences of the purchase, ownership and disposition of ADSs
    or ordinary shares in light of its particular circumstances,
    including the effect of any state, local or other national
    laws.
  Taxation
    of Dividends
   10




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Taxation
    of Capital Gains
      UK
    Stamp Duty and Stamp Duty Reserve Tax
    (SDRT)
     11




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US
    Information Reporting and Backup Withholding
  Form W-9
    UK
    Inheritance Tax
    Documents
    on display
  1-800-SEC-0330.
  Item 11.
    Quantitative
    and Qualitative Disclosures about Market Risk   12




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Item 12.
    Description
    of Securities Other than Equity Securities Depositary Fees and
    Charges    Persons Depositing or Withdrawing Shares Must Pay:

For:$5.00 per 100 ADSs (or portion of 100 ADSs)

Issuance of ADSs, including issuances resulting from a
    distribution of shares or rights or other property; cancellation
    of ADSs for the purpose of withdrawal, including if the deposit
    agreement terminates; distribution of securities distributed to
    holders of deposited securities which are distributed by the
    Depositary to ADS registered holders.$.02 or less per ADS (or a portion thereof)

Cash distributions to holders, except for distributions of cash
    dividends.Registration or transfer fees

Transfer and registration of shares on our share register to or
    from the name of the Depositary or its agent when they deposit
    or withdraw shares.Expenses of the Depositary

Cable, telex and facsimile transmissions (when expressly
    provided in the deposit agreement); converting foreign currency
    to US dollars.Taxes and other governmental charges the Depositary or the
    custodian has to pay on any ADS or share underlying an ADS, for
    example, stock transfer taxes, stamp duty or withholding taxes

As necessary.Any charges incurred by the Depositary or its agents for
    servicing the deposited securities

As necessary.   Depositary
    Payments to the Company
  out-of-pocket
       15252-8516
 1-800-466-7215
  13




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PART II  Item 13.
    Defaults,
    Dividend Arrearages and Delinquencies    Item 14.
    Material
    Modifications to the Rights of Security Holders and Use of
    Proceeds    Item 15.
    Controls
    and Procedures  A.
    Disclosure
    controls and procedures    B.
    Managements
    evaluation of the effectiveness of internal control over
    financial reporting  Rules 13a-15(f) 15d-15(f)
  Internal
    Control-Integrated Framework
  C.
    Independent
    auditor attestation  Form 20-F.
  D.
    Change in
    internal control over financial reporting   14




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Item 16.
    [Reserved]  Item 16A.
    Audit
    Committee Financial Expert    Item 16B.
    Code
    of Ethics    Item 16C.
    Principal
    Accountant Fees and Services    Year Ended

Year EndedMarch 31,

March 31,2010

2009(£m)Audit fees


8.4



9.7Audit related fees


0.2



0.3Tax fees


1.4



0.9All other fees


1.0



0.6Total


£11.0



£11.5         (1)

    
    The aggregate fees billed by PricewaterhouseCoopers LLP for the
    audit of the Companys financial statements and regulatory
    reporting for the fiscal year ended 31 March 2010 and the
    review of interim financial statements for the six months ended
    30 September 2009 were £8.4 million. Fees billed
    by PricewaterhouseCoopers LLP for the audit of the
    Companys financial statements and regulatory reporting for
    the fiscal year ended 31 March 2009 and the review of
    interim financial statements for the six months ended
    30 September 2008, were £9.7 million.(2)

    
    The aggregate fees billed by PricewaterhouseCoopers LLP for
    assurance and related services that were reasonably related to
    the performance of the audit or review of the Companys
    financial statements and are not disclosed under Audit
    Fees above were £0.2 million in fiscal 2009/10
    and £0.3 million in fiscal 2008/09. Included within
    the fees in fiscal 2009/10 are services principally related to
    comfort letters and SAS 70 control reports.(3)

    
    Aggregate fees billed by PricewaterhouseCoopers LLP for tax
    compliance, tax advice and tax planning were
    £1.4 million in fiscal 2009/10 and
    £0.9 million in fiscal 2008/09.(4)

    
    Aggregate fees billed by PricewaterhouseCoopers LLP for all
    other services in fiscal 2009/10 were £1.0 million.
    Other services include fees relating to corporate responsibility
    reporting, treasury related projects and sundry services, all of
    which have been subject to Audit Committee approval. Aggregate
    fees billed by PricewaterhouseCoopers LLP for all other services
    in fiscal 2008/09 were £0.6 million. 15




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Item 16D.
    Exemptions
    from the Listing Standards for Audit Committees    Item 16E.
    Purchases
    of Equity Securities by the Issuer and Affiliated
    Purchasers    (c). Total Number of

(d). Maximum NumberShares Purchased

of Shares (Rounded)(b). Average

as Part of Publicly

that May Yet Be(a). Total Number of

Price Paid

Announced Plans

Purchased Under thePeriods

Shares Purchased

per Share

or Programs

Plans or ProgramsNo securities were purchased by the Company during fiscal year
    2009/10.   Note
  Item 16F.
    Change
    in Registrants Certifying Accountant    Item 16G.
    Corporate
    Governance   PART III  Item 17.
    Financial
    Statements    Item 18.
    Financial
    Statements   16




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Report of
    Independent Registered Public Accounting Firm
    Form 20-F.
         17




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##### Table of Contents



Item 19.
    Exhibits  Form 20-F.
  Form 20-F,
 18




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##### Table of Contents



Description1.1

Articles of Association of National Grid plc adopted by Special
    Resolution passed on 27 July 2009, effective 1 October
    2009.

Filed herewith2(a)

Amended and restated Deposit Agreement dated as of 1 August
    2005 among National Grid plc and The Bank of New York.
    (Exhibit 2(a) to National Grid plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated By Reference2(b).1.1

Prospectus issued by National Grid plc and National Grid
    Electricity Transmission plc on 18 August 2005 relating to
    12,000,000,000 (previously 6,000,000,000) issuable
    under the Euro Medium Term Note Programme. (Exhibit 2
    (b).1.1 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).1.2

Supplementary Prospectus dated 26 August 2006.
    (Exhibit 2 (b).1.2 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).1.3

Supplementary Prospectus dated 17 November 2005.
    (Exhibit 2 (b).1.3 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).1.4

Supplementary Prospectus dated 6 March 2006.
    (Exhibit 2 (b).1.4 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).1.5

Supplementary Prospectus dated 12 May 2006. (Exhibit 2
    (b).1.5 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).1.6

Supplementary Prospectus dated 19 May 2006. (Exhibit 2
    (b).1.6 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).2.1

Prospectus issued by National Grid Gas Holdings plc and National
    Grid Gas plc on 24 February 2006 relating to
    10,000,000,000 issuable under the Euro Medium Term Note
    Programme. (Exhibit 2 (b).2.1 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).2.2

Supplementary Prospectus dated 6 March 2006.
    (Exhibit 2 (b).2.2 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).2.3

Supplementary Prospectus dated 22 May 2006. (Exhibit 2
    (b).2.3 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference2(b).3.1

Prospectus issued by National Grid plc and National Grid
    Electricity Transmission plc on 11 August 2006 relating to
    12,000,000,000 issuable under the Euro Medium Term Note
    Programme. (Exhibit 2 (c).1.1 to National Grid plc
    Form 20-F
    dated 19 June 2007 File
    No. 1-14958)

Incorporated by reference2(b).3.2

Supplementary Prospectus issued by National Grid plc and
    National Grid Electricity Transmission plc on 1 December
    2006 relating to 12,000,000,000 issuable under the Euro
    Medium Term Note Programme. (Exhibit 2 (c).1.2 to National
    Grid plc
    Form 20-F
    dated 19 June 2007 File
    No. 1-14958)

Incorporated by reference2(b).4.1

Prospectus issued by National Grid Gas Holdings plc and National
    Grid Gas plc and National Grid Gas Finance (No 1) plc on
    23 February 2007 relating to 10,000,000,000 issuable
    under the Euro Medium Term Note Programme. (Exhibit 2
    (d).1.1 to National Grid plc
    Form 20-F
    dated 19 June 2007 File
    No. 1-14958)

Incorporated by reference2(b).4.2

Supplementary Prospectus issued by National Grid Gas Holdings
    plc and National Grid Gas plc and National Grid Gas Finance (No
    1) plc on 4 February 2008 relating to
    10,000,000,000 issuable under the Euro Medium Term Note
    Programme. (Exhibit 2 (b).4.2 to National Grid plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated by reference 19




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Description2(b).5.1

Prospectus issued by National Grid plc and National Grid
    Electricity Transmission plc on 2 August 2007 relating to
    15,000,000,000 issuable under the Euro Medium Term Note
    Programme. (Exhibit 2 (b).5.1 to National Grid plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated by reference2(b).5.2

Supplementary Prospectus issued by National Grid plc and
    National Grid Electricity Transmission plc on 4 February
    2008 relating to 15,000,000,000 issuable under the Euro
    Medium Term Note Programme. (Exhibit 2 (b).5.2 to National
    Grid plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated by reference2(b).6.1

Prospectus issued by National Grid USA on 3 December 2007
    relating to 4,000,000,000 issuable under the Euro Medium
    Term Note Programme. (Exhibit 2 (b).6.1 to National Grid
    plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated by reference2(b).6.2

Supplementary Prospectus issued by National Grid USA on
    4 February 2008 relating to 4,000,000,000 issuable
    under the Euro Medium Term Note Programme. (Exhibit 2
    (b).6.2 to National Grid plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated by reference2(b).7.1

Prospectus issued by National Grid Gas plc and National Grid Gas
    Finance (No 1) plc on 26 February 2008 relating to
    10,000,000,000 issuable under the Euro Medium Term Note
    Programme. (Exhibit 2 (b).7.1 to National Grid plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated by reference2(b).7.2

Supplementary Prospectus issued by National Grid Gas plc and
    National Grid Gas Finance (No 1) plc on 20 October
    2008 relating to 10,000,000,000 issuable under the Euro
    Medium Term Note Programme. (Exhibit 2 (b).7.2 to National
    Grid plc
    Form 20-F
    dated 16 June 2009 File
    No. 1-14958)

Incorporated by reference2(b).8.1

Prospectus issued by National Grid plc and National Grid
    Electricity Transmission plc on 30 July 2008 relating to
    15,000,000,000 issuable under the Euro Medium Term Note
    Programme. (Exhibit 2 (b).8.1 to National Grid plc
    Form 20-F
    dated 16 June 2009 File
    No. 1-14958)

Incorporated by reference2(b).8.2

Supplementary Prospectus issued by National Grid plc and
    National Grid Electricity Transmission plc on 28 November
    2008 relating to 15,000,000,000 issuable under the Euro
    Medium Term Note Programme. (Exhibit 2 (b).8.2 to National
    Grid plc
    Form 20-F
    dated 16 June 2009 File
    No. 1-14958)

Incorporated by reference2(b).9.1

Prospectus issued by National Grid USA on 1 December 2008
    relating to 4,000,000,000 issuable under the Euro Medium
    Term Note Programme. (Exhibit 2 (b).9.1 to National Grid
    plc
    Form 20-F
    dated 16 June 2009 File
    No. 1-14958)

Incorporated by reference2(b).10.1

Prospectus issued by National Grid Gas plc on 24 February
    2009 relating to 10,000,000,000 issuable under the Euro
    Medium Term Note Programme. (Exhibit 2 (b).10.1 to National
    Grid plc
    Form 20-F
    dated 16 June 2009 File
    No. 1-14958)

Incorporated by reference2(b).11.1

Prospectus issued by National Grid plc and National Grid
    Electricity Transmission plc on 24 July 2009 relating to
    15,000,000,000 issuable under the Euro Medium Term Note
    Programme.

Filed herewith2(b).12.1

Prospectus issued by National Grid USA on 18 December 2009
    relating to 4,000,000,000 issuable under the Euro Medium
    Term Note Programme.

Filed herewith 20




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Description2(b).13.1

Prospectus issued by National Grid Gas plc on 24 February
    2010 relating to 10,000,000,000 issuable under the Euro
    Medium Term Note Programme.

Filed herewith4(a).1

Underwriting Agreement among National Grid plc and the
    underwriting banks named therein, dated as 20 May 2010.

Filed herewith4(c).1

Service Agreement among The National Grid Group plc, National
    Grid Company plc and Edward Astle dated 27 July 2001.
    (Exhibit 4.3 to National Grid Transco
    Form 20-F
    dated 16 June 2004
    File No. 1-14958)

Incorporated by reference4(c).2

Service Agreement among National Grid plc and Mark Fairbairn
    23 January 2007. (Exhibit 4(c).2 to National Grid
    Transco
    Form 20-F
    dated 19 June 2007 File
    No. 1-14958)

Incorporated by reference4(c).3

Service Agreement among The National Grid plc and Steven
    Holliday dated 1 April 2006. (Exhibit 4.(c).3 to
    National Grid Transco
    Form 20-F
    dated 19 June 2007 File
    No. 1-14958)

Incorporated by reference4(c).4

Service Agreement among National Grid Transco plc, National Grid
    USA and Michael E. Jesanis dated 8 July 2004.
    (Exhibit 4.5 to National Grid Transco
    Form 20-F
    dated 15 June 2005
    File No. 1-14958)

Incorporated by reference4(c).5

Service Agreement among National Grid Group plc, National Grid
    Company plc and Steve Lucas dated 13 June 2002.
    (Exhibit 4.5 to National Grid Transco
    Form 20-F
    dated 16 June 2004
    File No. 1-14958)

Incorporated by reference4(c).6

Service Agreement among The National Grid Group plc, National
    Grid Company plc and Roger J. Urwin dated as of 17 November
    1995. (Exhibit 4.7 to National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference4(c).7

Service Agreement among National Grid Transco plc, National Grid
    Company plc and Nicholas Winser dated 28 April 2003.
    (Exhibit 4.8 to National Grid Transco
    Form 20-F
    dated 16 June 2004
    File No. 1-14958)

Incorporated by reference4(c).8.1

Fixed Term Employment Agreement among National Grid plc,
    National Grid USA and Robert B. Catell dated 26 October
    2007. (Exhibit 4(b).8 to National Grid plc
    Form 20-F
    dated 17 June 2008
    File No. 1-14958)

Incorporated by reference4(c).8.2

Letter of Appointment  Robert B. Catell.
    (Exhibit 4(b).8.2 to National Grid plc
    Form 20-F
    dated 16 June 2009 File
    No. 1-14958)

Incorporated by reference4(c).9

Employment Agreement among National Grid plc, National Grid USA
    and Thomas King dated 11 July 2007. (Exhibit 4(c).9 to
    National Grid plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated by reference4(c).10

Letter of Appointment  Linda Adamany
    (Exhibit 4(c).9 to National Grid plc
    Form 20-F
    dated 19 June 2007 File
    No. 1-14958)

Incorporated by reference4(c).11

Letter of Appointment  Philip Aiken
    (Exhibit 4(c).11 to National Grid plc
    Form 20-F
    dated 17 June 2008 File
    No. 1-14958)

Incorporated by reference4(c).12.1

Letter of Appointment  John Allan (Exhibit 4.10
    to National Grid Transco
    Form 20-F
    dated 15 June 2005 File
    No. 1-14958)

Incorporated by reference4(c).12.2

Letter dated 7 March 2006 to John Allan relating to
    appointment as chairman of Remuneration Committee.
    (Exhibit 4(c).8.2 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference4(c).13.1

Letter of Appointment  John Grant (Exhibit 4.9
    to National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference 21




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Description4(c).13.2

Letter dated 7 March 2006 to John Grant relating to
    retirement as chairman of Remuneration Committee.
    (Exhibit 4 (c).9.2 to National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference4(c).14

Letter of Appointment  Ken Harvey (Exhibit 4.10
    to National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference4(c).15

Letter of Appointment  Paul Joskow (Exhibit 4.11
    to National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference4(c).16

Letter of Appointment  Sir John Parker
    (Exhibit 4.12 to National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference4(c).17

Letter of Appointment  Stephen Pettit
    (Exhibit 4.13 to National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference4(c).18

Letter of Appointment  Maria Richter
    (Exhibit 4.14 to National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference4(c).19

Letter of Appointment  George Rose (Exhibit 4.15
    to National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference4(c).20

National Grid plc Deferred Share Plan. (Exhibit 4 (c).16 to
    National Grid plc
    Form 20-F
    dated 20 June 2006 File
    No. 1-14958)

Incorporated by reference4(c).21

National Grid Executive Share Option Plan 2002 (Exhibit 4
    (c) to National Grid Group
    Form 20-F
    dated 21 June 2002 File
    No. 1-14958)

Incorporated by reference4(c).22

National Grid Group Share Matching Plan 2002 (Exhibit 4
    (c) to National Grid Group
    Form 20-F
    dated 21 June 2002 File
    No. 1-14958)

Incorporated by reference4(c).23

National Grid Transco Performance Share Plan 2002 (as approved
    23 July 2002 by a resolution of the shareholders of
    National Grid Group plc, adopted 17 October 2002 by a
    resolution of the Board of National Grid Group plc, amended
    26 June 2003 by the Share Schemes
    Sub-Committee
    of National Grid Transco plc, and amended 5 May 2004 by the
    Share Schemes
    Sub-Committee
    of National Grid Transco plc) (Exhibit 4.19 to National
    Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference4(c).24

National Grid Executive Share Option Scheme (Exhibit 4D to
    National Grid Group
    S-8 dated
    26 July 2001 File
    No. 333-65968)

Incorporated by reference4(c).25

Lattice Group Short Term Incentive Scheme (approved by a
    resolution of the shareholders of BG Group plc effective
    23 October 2000; approved by a resolution of the Board of
    National Grid Transco plc on 30 April 2004; amended by
    resolutions of the Board of Lattice Group plc effective on
    21 October 2002 and 13 May 2004) (Exhibit 4.23 to
    National Grid Transco
    Form 20-F
    dated 16 June 2004 File
    No. 1-14958)

Incorporated by reference8

List of subsidiaries

Filed herewith12.1

Certification of Steve Holliday

Filed herewith12.2

Certification of Steve Lucas

Filed herewith13

Certifications of Steve Holliday and Steve Lucas furnished
    pursuant to 18 U.S.C. Section 1350

Filed herewith15.1

National Grid plc Annual Report and Accounts 2009/10, in
    extracted form

Filed herewith15.2

Consent of PricewaterhouseCoopers LLP, independent registered
    public accounting firm to National Grid plc

Filed herewith  22




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SIGNATURE  Form 20-F
     By:
    /s/  Steve
    Lucas       23