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Exhibit 2(b).1.4
 SUPPLEMENTARY PROSPECTUS DATED 6 MARCH 2006
 
 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 6,000,000,000
 Euro Medium Term Note Programme
 Supplement Prospectus National Grid NGET Issuer Issuers FSMA th NGET
Supplement Programme




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2




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Acquisition of KeySpan
    Acquisition benefits
  
    
    KeySpans gas distribution and electricity distribution and transmission businesses
operate in states where National Grid already has a presence and where it has strong
regulatory relationships. The geographic fit between the two companies will facilitate the
implementation of efficiency initiatives across the enlarged Group.
    
    The Acquisition will allow National Grid to deploy its core skills of owning and
operating network infrastructure within an incentive-based regulatory environment across a
larger rate base.
  1
  
    
    Deliver identified integration savings of $200 million per year, through the
rationalisation of overlapping functions and the sharing of best practices.
    
    Unlock additional organic growth by investing in KeySpans gas distribution business.
    
    Invest in other growth opportunities including gas pipelines and storage.
 Generation
  
 1
    
    On a Business Performance basis. 3




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Management
  Financing
  Financial Results
 2
 Completion
   Amendment to the Terms and Conditions
  (ii)
    
    Delay in publication of Index if sub-paragraph (i) of the definition of Index Figure
is applicable: If the Index Figure which is normally published in the seventh month and
which relates to the eighth month (the relevant month) before the month in which a
payment is due to be made is not published on or before the fourteenth business day before
the date on which such payment is due (the date for payment), the Index Figure
applicable to the month in which the date for payment falls shall be (1) such substitute
index figure (if any) as the Trustee considers to have been published by the United
Kingdom Debt Management Office or the Bank of England, as the case may be, for the
purposes of indexation of payments on the Reference Gilt or, failing such publication, on
any one or more issues of index-linked Treasury Stock selected by an Indexation Adviser
(and approved by the Trustee) or (2) if no such determination is made by such Indexation
Adviser within seven days, the Index Figure last published (or, if later, the substitute
index figure last determined pursuant to Condition 4.3(i)) before the date for payment.(iii)
    
    Delay in publication of Index if sub-paragraph (ii) and/or (iii) of the definition
of Index Figure is applicable: If the Index Figure relating to any month (the calculation
month) which is required to be taken into account for the purposes of the determination
of the Index Figure for any date is not published on or before the fourteenth business day
before the date on which such payment is due (the date for payment), the Index Figure applicable for the relevant calculation month
shall be
 
 2
    
    US GAAP. 4




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(1) such substitute index figure (if any) as the Trustee considers to have been
published by the United Kingdom Debt Management Office or the Bank of England, as the
case may be, for the purposes of indexation of payments on the Reference Gilt or, failing
such publication, on any one or more issues of index-linked Treasury Stock selected by an
Indexation Adviser (and approved by the Trustee) or (2) if no such determination is made
by such Indexation Adviser within seven days, the Index Figure last published (or, if
later, the substitute index figure last determined pursuant to Condition 4.3(i)) before
the date for payment.
 5