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                                                                   Exhibit 10.1

                               PROMISSORY NOTE


$461,501.60                                                        March 7, 2002


        FOR VALUE RECEIVED, John A. Tillinghast, an individual with an address
of 77 Exeter Road, North Hampton, New Hampshire ("Maker"), hereby promises to
pay to the order of BayCorp Holdings, Ltd., a Delaware corporation, with a
principal place of business at 51 Dow Highway, Unit 7, Eliot, Maine ("Holder"),
at the Holder's business address, or at such other place as the Holder or any
subsequent holder hereof may in writing designate the principal sum of Four
Hundred Sixty-One Thousand, Five Hundred One Dollars and Sixty Cents
($461,501.60), with annual interest thereon from the date hereof on the
outstanding principal at the rate of interest stated below.  This Note is
entered into in connection with the Maker's exercise of nonstatutory stock
options and is secured by the parties' Stock Pledge Agreement of even date
herewith ("Pledge Agreement").

        1.      TERM.  This Note shall mature on the earlier of (i) December
31, 2003 or (ii) thirty (30) days following the payment to Great Bay Power
Corporation ("Great Bay"), Little Bay Power Corporation ("Little Bay"), BayCorp
Holdings, Ltd., or its common shareholders, as the case may be, of the proceeds
of the sale of (A) Great Bay's and Little Bay's interests in the Seabrook
Nuclear Generating Station or (B) BayCorp Holdings, Ltd.'s shares of capital
stock of Great Bay and Little Bay or (C) the outstanding shares of capital
stock of BayCorp Holdings, Ltd., by merger, share exchange or otherwise.  Upon
maturity, the outstanding principal balance, and all accrued but unpaid
interest, and other expenses, if any, shall be due and payable in full.

        2.      INTEREST RATE.  The interest rate on outstanding principal and
accrued but unpaid interest shall be five percent (5%) per annum, which
interest shall be compounded annually and shall accrue.

        3.      LIMITED RECOURSE NOTE.  The Maker shall be subject to personal
liability under this Note and the Holder shall be entitled to a corresponding
right of recourse against the Maker, provided that such personal liability
shall not exceed Five Thousand Dollars ($5,000). Except as provided in the
preceding sentence, this Note is a nonrecourse note and the Holder's sole
security is and sole recourse shall be against those shares of stock pledged by
the Maker to the Holder or its designee pursuant to the parties' Pledge
Agreement.

        4.      PREPAYMENT.  This Note may be prepaid in whole or in part
without any penalty.  No prepayment of less than the full unpaid balance of
principal and late charges, if any, shall relieve Maker of the obligation to
pay the next installment of principal hereunder.

        5.      LATE CHARGE.  In the event any payments required hereunder are
not paid when due, Maker shall, in addition to all other amounts then due, pay
a late charge (as liquidated damages) equal to five percent (5%) of the overdue
payment(s) of principal and interest.

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        Acceptance by the Holder of payment of the late charge shall not be
deemed a waiver of any default.

        6.      APPLICATION OF PAYMENTS.  All payments by Maker hereunder shall
be applied first to late charges, if any, then to accrued interest and then to
principal due in accordance with the terms hereof.

        7.      EVENTS OF DEFAULT.  Upon the occurrence of any of the following
events of default, all sums payable under this Note shall, at the option of the
Holder, become immediately due and payable without further notice or demand:

                7.1     Failure to pay the principal of, or fees or interest
        on, the Note, as the same shall become due and payable, and a
        continuation of such default for ten (10) days after written notice
        thereof.

                7.2     Default in the due observance or performance of any
        other covenant, condition or agreement, on the part of the Maker to
        be observed or  performed pursuant to the terms hereof, or the Pledge
        Agreement, and a continuation of such default for thirty (30)
        days after notice thereof.

                7.3     The Maker shall (i) apply for or consent to the
        appointment of a receiver, trustee or liquidator of any of his
        property, (ii) admit in writing his inability to pay his debts as they
        mature, (iii) make a general assignment for the benefit of creditors,
        (iv) be adjudicated a bankrupt or insolvent or  (v) file a voluntary
        petition in bankruptcy, or a petition or an answer seeking an
        arrangement with creditors or to take advantage of any bankruptcy,
        insolvency, readjustment of debt, or liquidation law or statute, or an
        answer  admitting the material allegations of a petition filed against
        him in any proceeding under any such law.

                7.4     An order, judgment or decree shall be entered, without
        the application, approval or consent of the Maker by any court of
        competent jurisdiction, approving a petition seeking reorganization or
        approving the appointment of a receiver, trustee or liquidator of all
        or a substantial part of his assets, and such order, judgment or
        decree shall continue unstayed and in effect for any period of
        ninety (90) days.

        8.      WAIVERS.  The Maker hereof  waives presentment, protest and
demand, notice of protest, demand and dishonor and nonpayment of this Note, and
agrees to pay all costs of collection when incurred, including reasonable
attorneys' fees.

        9.      DELAYS AND OMISSIONS.  No delay or omission on the part of the
Holder in exercising any right hereunder shall operate as a waiver of such
right, or of any other right of the Holder, nor shall any delay, omission or
waiver on any one occasion be deemed a bar to or waiver of the same or any
other right on any future occasion.  No single or partial exercise of a power
hereunder shall preclude other exercises thereof, or the exercises of any other
power hereunder.


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        10.     CHOICE OF LAW.  This Note shall be governed exclusively by the
laws of the State of New Hampshire.  Maker hereby agrees that any action hereon
or relating hereto may be maintained in a court of competent subject-matter
jurisdiction located in that state, and consents to the jurisdiction of any
such court for all purposes connected herewith.

        11.     ASSIGNMENT; BINDING EFFECT.  This Note is not assignable by the
Maker.  This Note is binding upon the Maker and his heirs and legal
representatives, and shall inure to the benefit of the Holder, its successors
and assigns.

        IN WITNESS WHEREOF, Maker has executed this Note as of the date first
written above.




                                             /s/ John A. Tillinghast
                                             ---------------------------
                                             John A. Tillinghast