National Grid plc Employee Stock Purchase Plan

I am pleased to announce that beginning January 1 , 201 1 the discount currently offered by the company to purchase National Grid American Depositary Shares (ADSs) through the ESPP will increase from 10% to 15%.

The purpose of this letter is to inform you of the increase to the discount, remind you of the benefits of participating in the Plan and bring your attention to the revised employee guide enclosed.

As well as having the ability to purchase ADSs at a 15% discount, you will also have the opportunity to reinvest cash dividends and purchase ADSs at the discounted rate. In addition to the discount, this Plan provides a way for you to directly participate in the future success of National Grid and is another key part of your Total Rewards package.

Under the ESPP you may contribute up to $18,888 in any tax year from your post tax pay to buy ADSs in the company via Bank of New York Mellon (BNYM) who administers the Plan on the company's behalf. Overall deductions must not exceed 20% of your base pay.

To join the ESPP, you first need to decide how much you would like to contribute, bearing in mind the overall limits set out above.

You can either register on-line via the BNYM website or by telephone:

Website address: www.bnymellon.com/shareowner/equityaccess

Telephone No. 866-418-5145 Both methods require an access ID and Personal Identification Number (PIN). Your access ID is your Employee ID with NGG preceding it (i.e. NGG100000099 or NGG99999) and your PIN number is contained in the additional letter enclosed.

Full details of how the Plan operates are contained in the enclosed employee guide, however, should you have any further questions, please contact BNYM on the above telephone number.

I hope you will take the time to read the employee guide and consider joining the Plan.

Yours sincerely,

Mike Westcott

Global HR DirectorFamily Care