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                                                                    EXHIBIT 10.3

                               AGREEMENT TO AMEND

      THIS AGREEMENT TO AMEND is made and entered into as of July 23, 2002 by
and between Great Bay Power Corporation, a New Hampshire corporation, ("GBPC"),
and Unitil Power Corp., a New Hampshire corporation, ("Unitil Power").

      WHEREAS GBPC and Unitil Power are parties to a Purchased Power Agreement
dated as of April 26, 1993 (the "PPA"); and

      WHEREAS the parties desire to amend and restate the PPA, as more
particularly provided for hereafter;

      NOW, THEREFORE, in consideration of the premises and mutual obligations
and undertakings set forth herein, and for other good and valuable
consideration, the receipt and adequacy of which is hereby acknowledged, the
parties agree as follows:

      1. Amendment of PPA. The parties hereby agree that, subject to the
satisfaction of the conditions precedent set forth in Section 4, below,
effective as of December 1, 2002, they shall enter into the Amended and Restated
Purchased Power Agreement (the "Amended and Restated PPA") in the form attached
hereto as Exhibit A; provided, however, that GBPC may elect an earlier effective
date of the Amended and Restated PPA, assuming satisfaction of the conditions
precedent set forth in Section 4, below, by written notice delivered to Unitil
Power not less than five days prior to such earlier effective date; and
provided, further, that if the conditions precedent set forth in Section 4 below
are not satisfied on or before December 1, 2002, then, subject to the
termination provisions set forth in said Section 4, the effective date of the
Amended and Restated PPA shall be that date which is two business days following
the date on which all of such conditions precedent have been satisfied. The date
on which the Amended and Restated PPA is effective shall be the "Commencement
Date".

      2. Until the Commencement Date, the PPA shall remain in effect in
accordance with its terms and the parties shall continue to perform their
obligations thereunder. In the event that for any reason including, without
limitation, a termination of this Agreement pursuant to Section 4, below, the
parties do not enter into the Amended and Restated PPA, then the PPA shall
remain in effect in accordance with its terms. Following the Commencement Date,
the provisions of the PPA shall remain in effect as appropriate with respect to
all transactions between the parties occurring prior to the Commencement Date
under the PPA.

      3. Release of Mortgage and Security Interest. On the Commencement Date,
the Third Mortgage and Security Agreement between the parties dated as of
December 22, 1993 (the "Mortgage") shall be terminated and Unitil Power hereby
agrees to execute and deliver to GBPC on such date a mortgage discharge and UCC
termination statements in forms appropriate for filing.

      4. Conditions Precedent; Termination. The obligation of the parties to
enter into the Amended and Restated PPA and termination of the Mortgage
contemplated by Section 3 hereof shall be and are subject to and conditioned on:
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      (A) the acceptance for filing by the Federal Energy Regulatory Commission
("FERC") of the Amended and Restated PPA without conditions or changes to the
MWh and MW purchases or to the rates set forth therein; and

      (B) the delivery by GBPC to Unitil Power of the Letter of Credit
contemplated by Section 11.2 of the Amended and Restated PPA.

      In the event that prior to December 31, 2002 FERC:

                  i. does not accept the Amended and Restated PPA without
modification of any MWh or MW purchase or any rate set forth therein;

                  ii. sets a refund effective date under Section 206(b) of the
Federal Power Act; or

                  iii. takes any action that imposes a refund obligation upon
GBPC with respect to the Amended and Restated PPA;

then GBPC or Unitil Power may at any time thereafter terminate this Agreement
without any liability to the other party for such termination, the obligation of
the parties to enter into the Amended and Restated PPA shall accordingly
terminate, and the PPA shall remain in effect in accordance with its terms. Each
of GBPC and Unitil Power agree that, except with the prior written consent of
the other party, it will not, and will use its best efforts to ensure that its
affiliates will not, institute or voluntarily cooperate in the institution or
conduct of any action or proceeding of FERC under Part II, Section 206, or any
other provision, of the Federal Power Act, which action or proceeding is
intended for the purpose of, or could reasonably be expected to have the effect
of changing the terms of the Amended and Restated PPA.

      5. Modification; Waiver. This Agreement may be modified only by an
instrument in writing signed by duly authorized representatives of both parties.
Delay or failure of either party to enforce any provision of this Agreement, or
to require performance by the other party of any provision hereof, shall not be
construed as a waiver of such provision, or any other provision, or affect the
validity of this Agreement.

      6. Binding Effect. The provisions, covenants and agreements herein
contained will inure to the benefit of, and be binding upon, the parties hereto
and their respective successors and assigns.

      7. Governing Law. This Agreement shall be governed and interpreted
according to the laws of the State of New Hampshire.

      8. Counterparts. This Agreement may be executed in two or more
counterparts, each of which will be deemed and original, but all of which
collectively constitute one and the same agreement.
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      IN WITNESS WHEREOF, the parties have caused this Agreement to be signed by
their respective authorized officers as of the date first written above.


GREAT BAY POWER CORPORATION                 UNITIL POWER CORP.


By:        /S/ Anthony M. Callendrello      By:        /S/ David K. Foote
   -------------------------------------       ---------------------------------
Name:      Anthony M. Callendrello          Name:      David K. Foote
     -----------------------------------         -------------------------------
Title:     Vice President                   Title:     President
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