Blocklisting Interim Review

National Grid PLC
13 August 2007



National Grid plc ('NG')

13th August 2007

-----------------------------------------------------

Block Listing Six Monthly Return

-----------------------------------------------------

NB: References are to NG Ordinary shares of 1117/43p.
1. Name of Company                                      National Grid plc
2. Name of Scheme                                       Employee Shareschemes
3. Period                                               1 February 2007 to 31 July 2007
4. Shares not issued at end of last period:

                                                        487,617

                                                        Plus additional blocklisting of 5 million shares on 14
                                                        February 2007
5. Shares issued/allotted during period:                4,137,105
6. Balance not yet issued/allotted at end of period:    1,350,512
7. No. of shares originally listed and date of          On 1 August 2005, following NG's capital consolidation,
admission:                                              a total of 2,712,727,627 New Ordinary Shares of 11 17/43
                                                        pence were in issue.

Total number of shares in issue at end of the period: 2,656,395,076 (following
the repurchase and cancellation of 61,820,959 shares in the period). In addition
a total of 14 million shares were repurchased and held in Treasury. Following
transfers to sharescheme participants, the balance of Treasury shares at 31 July
2007 was 13,905,602 with resulting voting share capital being 2,642,489,474.

-----------------------------------------------------------------

Contact: D C Forward, Assistant Secretary

Tel: [phone]


National Grid plc ('NG')

13th August 2007

-----------------------------------------------------

Block Listing Six Monthly Return

-----------------------------------------------------

NB: References are to NG Ordinary shares of 1117/43p.
1. Name of Company                                      National Grid plc
2. Name of Scheme                                       National Grid Electricity Transmission plc-

                                                        4.25 per cent Exchangeable Bonds 2008.
3. Period                                               1 February 2007 to 31 July 2007.
4. Shares not issued at end of last period:

                                                        37,388
5. Shares issued/allotted during period:                  Nil
6. Balance not yet issued/allotted at end of period:    37,388
7. No. of shares originally listed and date of          On 1 August 2005, following NG's capital consolidation,
admission:                                              a total of 2,712,727,627 New Ordinary Shares of 11 17/43
                                                        pence were in issue.

Total number of shares in issue at end of the period: 2,656,395,076 (following
the repurchase and cancellation of 61,820,959 shares in the period). In addition
a total of 14 million shares were repurchased and held in Treasury. Following
transfers to sharescheme participants, the balance of Treasury shares at 31 July
2007 was 13,905,602 with resulting voting share capital being 2,642,489,474.

-----------------------------------------------------------------

Contact: D C Forward, Assistant Secretary

Tel: [phone]


                      This information is provided by RNS
            The company news service from the London Stock Exchange        RILFIDTFIVLID