<PAGE>
                                                                     EXHIBIT 2.2

        THE TRANSFER OF THIS AGREEMENT IS SUBJECT TO CERTAIN PROVISIONS
             CONTAINED HEREIN AND TO RESALE RESTRICTIONS UNDER THE
                       SECURITIES ACT OF 1933, AS AMENDED



                                 STOCK OPTION AGREEMENT


     Stock Option Agreement, dated as of March 23, 1998 (the "Agreement"), by
                                                              ---------
and between Sandwich Bancorp, Inc. ("Issuer"), a Massachusetts corporation and
                                     ------
bank holding company and the parent of the Sandwich Co-operative Bank, a
Massachusetts co-operative bank ("Sandwich Bank"), and The 1855 Bancorp
                                  -------------
("Grantee"), a Massachusetts mutual holding company and the parent of Compass
---------
Bank For Savings, a Massachusetts savings bank ("Compass Bank").
                                                 ------------


                                 WITNESSETH:


     WHEREAS, Issuer, Grantee, Compass Bank and Sandwich Bank have entered into
an Amended and Restated Affiliation and Merger Agreement dated as of March 23,
1998 (the "Affiliation Agreement"), providing for, among other things, the
           ---------------------
merger of Issuer with Grantee or an Affiliate of Grantee (the "Merger"); and
                                                               ------

     WHEREAS, as a condition and inducement to Grantee's execution of the
Affiliation Agreement, Grantee has required that Issuer agree, and Issuer has
agreed, to grant to Grantee the Option (as hereinafter defined); and

     NOW THEREFORE, in consideration of the foregoing and the respective
representations, warranties, covenants and agreements set forth herein and in
the Affiliation Agreement, and intending to be legally bound hereby, Issuer and
Grantee agree as follows:

     1  DEFINED TERMS.  Capitalized terms which are used but not defined herein
shall have the meanings ascribed to such terms in the Affiliation Agreement.

     2.  GRANT OF OPTION.  Subject to the terms and conditions set forth herein,
Issuer hereby grants to Grantee an irrevocable option (the "Option") to purchase
                                                            ------
up to 387,107 shares (as adjusted as set forth herein, the "Option Shares,"
                                                            -------------
which shall include the Option Shares before and after any transfer of such
Option Shares) of Common Stock, par value $1.00 per share ("Issuer Common
                                                            -------------
Stock"), of Issuer at a purchase price per Option Share (the "Purchase Price")
                                                              --------------
of $57.00, provided, however, that in no event shall the number of Option Shares
for which the Option is exercisable exceed 19.9% of the issued and outstanding
shares of Issuer Common Stock without giving effect to any shares subject to or
issued pursuant to the Option. The number of shares of Issuer Common Stock that
may be received upon the exercise of the Option and the Purchase Price are
subject to adjustment as herein set forth.

     3.  EXERCISE OF OPTION.

     (a)  Grantee or Holder (as hereinafter defined) may exercise the Option, in
whole or in part, at any time and from time to time following the occurrence of
a Purchase Event (as hereinafter defined) and before an Exercise Termination
Event (as hereinafter defined).  Each of the following shall be an "Exercise
Termination Event":


     (i)  The Effective Time (as defined in the Affiliation Agreement) of the
     Merger,

     (ii)  The passage of 12 months after termination of the Affiliation
     Agreement following the occurrence of a Purchase Event or a Preliminary
     Purchase Event;
<PAGE>

     (iii)  The date on which the Affiliation Agreement is terminated in
     accordance with its terms, but only if such termination takes place prior
     to the occurrence of a Purchase Event or a Preliminary Purchase Event; and

     (iv)  The passage of 12 months after the Affiliation Agreement is
     terminated by Grantee pursuant to Section 11.1.2 or 11.1.3 of the
     Affiliation Agreement.


Any purchase of shares upon exercise of the Option shall be subject to
compliance with applicable laws, including without limitation the Bank Holding
Company Act of 1956, as amended (the "BHC Act"), and the Bank Merger Act, as
                                      -------
amended ("Bank Merger Act").  The term "Holder" shall mean the holder or holders
          ---------------               ------
of the Option from time to time (subject to the limitations contained in Section
12(h)). The Grantee is the initial Holder.  The rights set forth in Section 8
hereof shall terminate when the right to exercise the Option terminates (other
than as a result of a complete exercise of the Option) as set forth above.


     (b)  As used herein, a "Purchase Event" means any of the following events:
                             --------------


        (i)  Without Grantee's prior written consent, Issuer shall have
     authorized, recommended or publicly proposed, or publicly announced an
     intention to authorize, recommend or propose, or entered into an agreement
     with any person (other than Grantee or any subsidiary of Grantee) to effect
     (A) a merger, consolidation or similar transaction involving Issuer or any
     of its subsidiaries, (B) the disposition, by sale, lease, exchange or
     otherwise, of assets of Issuer or any Issuer Subsidiary representing in
     either case 15% or more of the consolidated assets of Issuer and the Issuer
     Subsidiaries, or (C) the issuance, sale or other disposition of (including
     by way of merger, consolidation, share exchange or any similar transaction)
     securities representing 15% or more of the voting power of Issuer or any of
     the Issuer Subsidiaries (any of the foregoing an "Acquisition
                                                       -----------
     Transaction"); or

        (ii)  any person (other than Grantee or any subsidiary of Grantee) shall
     have acquired beneficial ownership (as such term is defined in Rule 13d-3
     promulgated under the Exchange Act) of or the right to acquire beneficial
     ownership of, or any "group" (as such term is defined in Section 13(d)(3)
                           -----
     of the Exchange Act) shall have been formed which beneficially owns or has
     the right to acquire beneficial ownership of, 25% or more of the then
     outstanding shares of Issuer Common Stock.


     (c)  As used herein, a "Preliminary Purchase Event" means any of the
                             --------------------------
following events:


        (i)  any person (other than Grantee or any subsidiary of Grantee) shall
     have commenced (as such term is defined in Rule 14d-2 under the Exchange
     Act), or shall have filed a registration statement under the Securities Act
     with respect to, a tender offer or exchange offer to purchase any shares of
     Issuer Common Stock such that, upon consummation of such offer, such person
     would own or control 10% or more of the then outstanding shares of Issuer
     Common Stock (such an offer being referred to herein as a "Tender Offer"
                                                                ------------
     and an "Exchange Offer," respectively); or
             --------------


        (ii) following the public announcement of an Acquisition Proposal (which
     the parties hereto acknowledge has already taken place), the holders of
     Issuer Common Stock shall not have approved the Affiliation Agreement at
     the meeting of such stockholders held for the purpose of voting on the
     Affiliation Agreement (the term "Acquisition Proposal" is defined to mean
                                      --------------------

                                      -2-
<PAGE>

     (x) a bona fide proposal by any person (other than Grantee or any
     subsidiary of Grantee) shall have been made to Issuer or its stockholders
     to engage in a Acquisition Transaction, (y) any person (other than Grantee
     or any subsidiary of Grantee) shall have stated its intention to Issuer or
     its stockholders to make a proposal to engage in a Acquisition Transaction
     if the Affiliation Agreement terminates or (z) any person (other than
     Grantee or any subsidiary of Grantee) shall have filed an application or
     notice with any Governmental Entity to engage in a Acquisition
     Transaction); or

        (iii)  following the occurrence of an Acquisition Proposal (which the
     parties hereto acknowledge has already taken place):


           (A) the meeting of Issuer stockholders held for the purpose of voting
        on the Affiliation Agreement shall not have been held or shall have been
        canceled prior to termination of the Affiliation Agreement,

           (B) Issuer's Board of Directors shall have withdrawn or modified, or
        publicly announced its intention to withdraw or modify, in a manner
        adverse to Grantee the recommendation of Issuer's Board of Directors
        with respect to the Affiliation Agreement and the Merger;

           (C)  Issuer shall have breached any representation, warranty,
        covenant or obligation contained in the Affiliation Agreement and such
        breach would entitle Grantee to terminate the Affiliation Agreement
        under Section 11.1.2 or 11.1.3 of the Affiliation Agreement (without
        regard to the cure period provided for therein unless such cure is
        promptly effected without jeopardizing consummation of the Merger
        pursuant to the terms of the Affiliation Agreement); or

           (D)  The Merger shall not have been consummated by reason of failure
        of the pooling of interests condition, and such failure is the result of
        the actions of a party not affiliated with either Grantee or Issuer; or


        (iv) any person other than Grantee or any Grantee Subsidiary, other than
     in connection with a transaction to which Grantee has given its prior
     written consent, shall have (x) acquired beneficial ownership or the right
     to acquire beneficial ownership of 10% or more of the outstanding shares of
     Issuer Common Stock or (y) filed an application or notice with the Federal
     Reserve Board, or other federal or state bank regulatory authority, which
     application or notice has been accepted for processing, for approval to
     acquire beneficial ownership of 10% or more of the outstanding shares of
     Issuer Common Stock or otherwise to engage in an Acquisition Transaction.


     As used in this Agreement, "person" shall have the meaning specified in
                                 ------
Sections 3(a)(9) and 13(d)(3) of the Exchange Act.

     (d)  Issuer shall notify Grantee promptly in writing of the occurrence of
any Preliminary Purchase Event or Purchase Event, it being understood that the
giving of such notice by Issuer shall not be a condition to the right of Holder
to exercise the Option.


     (e)  In the event Holder wishes to exercise the Option, it shall send to
Issuer a written notice (the date of which being herein referred to as the

"Notice Date") specifying (i) the total number of Option Shares it intends to
------------

                                      -3-
<PAGE>

purchase pursuant to such exercise, and (ii) a place and date not earlier than
three business days nor later than 15 business days from the Notice Date for the
closing (the "Closing") of such purchase (the "Closing Date").  If prior
              -------                          ------------
notification to or approval of the Board of Governors of the Federal Reserve
System (the "Federal Reserve Board"), the Federal Deposit Insurance Corporation,
             ---------------------
the Massachusetts Division of Banks, or any other Governmental Entity is
required in connection with such purchase, Issuer shall cooperate with Grantee
in the filing of the required notice of application for approval and the
obtaining of such approval and the Closing shall occur immediately following
such regulatory approvals (and any mandatory waiting periods). Any exercise of
the Option shall be deemed to occur on the Notice Date relating thereto.

     4.  PAYMENT AND DELIVERY OF CERTIFICATES.

     (a)  On each Closing Date, Holder shall (i) pay to Issuer, in immediately
available funds by wire transfer to a bank account designated by Issuer, an
amount equal to the Purchase Price multiplied by the number of Option Shares to
be purchased on such Closing Date, and (ii) present and surrender this Agreement
to Issuer at the address of Issuer specified in Section 12(f) hereof.

     (b)  At each Closing, simultaneously with the delivery of immediately
available funds and surrender of this Agreement as provided in Section 4(a), (i)
Issuer shall deliver to Holder (A) a certificate or certificates representing
the Option Shares to be purchased at such Closing, which Option Shares shall be
free and clear of all liens, claims, charges and encumbrances of any kind
whatsoever and subject to no preemptive rights, and (B) if the Option is
exercised in part only, an executed new agreement with the same terms as this
Agreement evidencing the right to purchase the balance of the shares of Issuer
Common Stock purchasable hereunder, and (ii) Holder shall deliver to Issuer a
letter agreeing that Holder shall not offer to sell or otherwise dispose of such
Option Shares in violation of applicable federal and state law or of the
provisions of this Agreement.

     (c)  In addition to any other legend that is required by applicable law,
certificates for the Option Shares delivered at each Closing shall be endorsed
with a restrictive legend which shall read substantially as follows:


           THE TRANSFER OF THE STOCK REPRESENTED BY THIS CERTIFICATE IS SUBJECT
        TO RESTRICTIONS ARISING UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
        AND PURSUANT TO THE TERMS OF A STOCK OPTION AGREEMENT DATED AS OF MARCH
        23, 1998.  A COPY OF SUCH AGREEMENT WILL BE PROVIDED TO THE HOLDER
        HEREOF WITHOUT CHARGE UPON RECEIPT BY ISSUER OF A WRITTEN REQUEST
        THEREFOR.


It is understood and agreed that: (i) the reference to the resale restrictions
of the Securities Act of 1933, as amended (the "1933 Act"), in the above legend
shall be removed by delivery of substitute certificate(s) without such reference
if Holder shall have delivered to Issuer a copy of a letter from the staff of
the SEC, or an opinion of counsel, in form and substance reasonably satisfactory
to Issuer, to the effect that such legend is not required for purposes of the
1933 Act; (ii) the reference to the provisions to this Agreement in the above
legend shall be removed by delivery of substitute certificate(s) without such
reference if the shares have been sold or transferred in compliance with the
provisions of this Agreement and under circumstances that do not require the
retention of such reference; and (iii) the legend shall be removed in its
entirety if the conditions in the preceding clauses (i) and (ii) are both
satisfied. In addition, such certificates shall bear any other legend as may be
required by law.

                                      -4-
<PAGE>

     (d)  Upon the giving by Holder to Issuer of the written notice of exercise
of the Option provided for under Section 3(e), the tender of the applicable
purchase price in immediately available funds and the tender of this Agreement
to Issuer, Holder shall be deemed to be the holder of record of the shares of
Issuer Common Stock issuable upon such exercise, notwithstanding that the stock
transfer books of Issuer shall then be closed or that certificates representing
such shares of Issuer Common Stock shall not then be actually delivered to
Holder.


     (e)  Issuer agrees (i) that it shall at all times maintain, free from
preemptive rights, sufficient authorized but unissued or treasury shares of
Issuer Common Stock so that the Option may be exercised without additional
authorization of Issuer Common Stock so that the Option may be exercised without
requiring Issuer's stockholders to approve an increase in the number of
authorized shares of Issuer Common Stock after giving effect to all other
options, warrants, convertible securities and other rights to purchase Issuer
Common Stock, (ii) that it will not, by charter amendment or through
reorganization, consolidation, merger, dissolution or sale of assets, or by any
other voluntary act, avoid or seek to avoid the observance or performance of any
of the covenants, stipulations or conditions to be observed or performed
hereunder by Issuer, (iii) promptly to take all action as may from time to time
be required (including (A) complying with all premerger notification, reporting
and waiting period requirements and (B) in the event prior approval of or notice
to any Governmental Entity is necessary before the Option may be exercised,
cooperating fully with Holder in preparing such applications or notices and
providing such information to such Governmental Entity as it may require) in
order to permit Holder to exercise the Option and Issuer duly and effectively to
issue shares of Issuer Common Stock pursuant hereto, and (iv) promptly to take
all action provided herein to protect the rights of Holder against dilution.

     5.  REPRESENTATIONS AND WARRANTIES OF ISSUER.  Issuer hereby represents and
warrants to Grantee (and Holder, if different than Grantee) as follows:

     (a) CORPORATE POWER AND AUTHORITY.  Issuer has all requisite corporate
power and authority to enter into this Agreement, and subject to any approvals
referred to herein, to consummate the transactions contemplated hereby.  The
execution and delivery of this Agreement and the consummation of the
transactions contemplated hereby have been duly authorized by all necessary
corporate action on the part of Issuer, and this Agreement has been duly
executed and delivered by Issuer.

     (b)  NO VIOLATIONS.  The execution and delivery of this Agreement, the
consummation of the transactions contemplated hereby and compliance by Issuer
with any of the provisions hereof will not (i) conflict with or result in a
breach of any provision of its Articles of Organization or Bylaws or a default
(or give rise to any right of termination, cancellation or acceleration) under
any of the terms, conditions or provisions of any note, bond, debenture,
mortgage, indenture, license, material agreement or other material instrument or
obligation to which Issuer is a party, or by which it or any of its properties
or assets may be bound, or (ii) violate any order, writ, injunction, decree,
statute, rule or regulation applicable to Issuer or any of its properties or
assets.

     (c)  AUTHORIZED STOCK.  Issuer has taken all necessary corporate and other
action to authorize and reserve and to permit it to issue, and at all times from
the date hereof until the obligation to deliver Issuer Common Stock upon the
exercise of the Option terminates, will have

                                      -5-
<PAGE>

reserved for issuance upon exercise of the Option that number of shares of
Issuer Common Stock equal to the maximum number of shares of Issuer Common Stock
at any time and from time to time purchasable upon exercise of the Option, and
all such shares, upon issuance pursuant to the Option, will be duly and validly
issued, fully paid and nonassessable, and will be delivered free and clear of
all liens, claims, charges and encumbrances of any kind or nature whatsoever and
not subject to any preemptive rights.

     6.  REPRESENTATIONS AND WARRANTIES OF GRANTEE.  Grantee hereby represents
and warrants to Issuer as follows:

     (a) CORPORATE POWER AND AUTHORITY.  Grantee has all requisite corporate
power and authority to enter into this Agreement and, subject to any approvals
or consents referred to herein, to consummate the transactions contemplated
hereby.  The execution and delivery of this Agreement and the consummation of
the transactions contemplated hereby have been duly authorized by all necessary
corporate action on the part of Grantee, and this Agreement has been duly
executed and delivered by Grantee.

     (b) The Option is not being, and any shares of Issuer Common Stock or other
securities acquired by Grantee upon exercise of the Option will not be, acquired
with a view to the public distribution thereof and will not be transferred or
otherwise disposed of except in a transaction registered or exempt from
registration under the 1933 Act.

     7.  ADJUSTMENT UPON CHANGES IN ISSUER CAPITALIZATION, ETC.

     (a)  In the event of any change in Issuer Common Stock by reason of a stock
dividend, stock split, split-up, recapitalization, combination, exchange of
shares or similar transaction, the type and number of shares or securities
subject to the Option, and the Purchase Price therefor, shall be adjusted
appropriately, and proper provision shall be made in the agreements governing
such transactions so that Holder shall receive, upon exercise of the Option, the
number and class of shares or other securities or property that Holder would
have received in respect of Issuer Common Stock if the Option had been exercised
immediately prior to such event, or the record date therefor, as applicable.  If
any additional shares of Issuer Common Stock are issued after the date of this
Agreement (other than pursuant to an event described in the first sentence of
this Section 7(a)), the number of shares of Issuer Common Stock subject to the
Option shall be adjusted so that, after such issuance, it, together with any
shares of Issuer Common Stock previously issued pursuant hereto, equals 19.9% of
the number of shares of Issuer Common Stock then issued and outstanding, without
giving effect to any shares subject to or issued pursuant to the Option.

     (b)  In the event that Issuer shall enter into an agreement:  (i) to
consolidate with or merge into any person, other than Grantee or one of its
subsidiaries, and shall not be the continuing or surviving corporation of such
consolidation or merger, (ii) to permit any person, other than Grantee or one of
its subsidiaries, to merge into Issuer and Issuer shall be the continuing or
surviving corporation, but, in connection with such merger, the then outstanding
shares of Issuer Common Stock shall be changed into or exchanged for stock or
other securities of Issuer or any other person or cash or any other property or
the outstanding shares of Issuer Common Stock immediately prior to such merger
shall after such merger represent less than 50% of the outstanding shares and
share equivalents of the merged company, or (iii) to sell or otherwise transfer
all or substantially all of its assets to any person, other than Grantee or one
of its subsidiaries, then, and in each such case, the

                                      -6-
<PAGE>

agreement governing such transaction shall make proper provisions so that the
Option shall, upon the consummation of any such transaction and upon the terms
and conditions set forth herein, be converted into, or exchanged for, an option
(the "Substitute Option"), at the election of Holder, of any of (x) the
      -----------------
Acquiring Corporation (as hereinafter defined), (y) any person that controls
the Acquiring Corporation or (z) in the case of a merger described in clause
(ii), Issuer (such person being referred to as "Substitute Option Issuer").
                                                ------------------------

     (c)  The Substitute Option shall have the same terms as the Option,
provided that, if the terms of the Substitute Option cannot, for legal reasons,
be the same as the Option, such terms shall be as similar as possible and in no
event less advantageous to Holder.  Substitute Option Issuer also shall enter
into an agreement with Holder in substantially the same form as this Agreement,
which shall be applicable to the Substitute Option.

     (d)  The Substitute Option shall be exercisable for such number of shares
of Substitute Common Stock (as hereinafter defined) as is equal to the Assigned
Value (as hereinafter defined) multiplied by the number of shares of Issuer
Common Stock for which the Option was theretofore exercisable, divided by the
Average Price (as hereinafter defined).  The exercise price of Substitute Option
per share of Substitute Common Stock (the "Substitute Option Price") shall then
                                           -----------------------
be equal to the Purchase Price multiplied by a fraction in which the numerator
is the number of shares of Issuer Common Stock for which the Option was
theretofore exercisable and the denominator is the number of shares of the
Substitute Common Stock for which the Substitute Option is exercisable.

     (e)  The following terms have the meanings indicated:

        (1)  "Acquiring Corporation" shall mean (i) the continuing or surviving
              ---------------------
     corporation of a consolidation or merger with Issuer (if other than
     Issuer), (ii) Issuer in a merger in which Issuer is the continuing or
     surviving person, or (iii) the transferee of all or substantially all of
     Issuer's assets (or a substantial part of the assets of its subsidiaries
     taken as a whole).

        (2)  "Substitute Common Stock" shall mean the shares of capital stock
              -----------------------
     (or similar equity interest) with the greatest voting power in respect of
     the election of directors (or persons similarly responsible for the
     direction of the business and affairs) of the Substitute Option Issuer.

        (3)  "Assigned Value" shall mean the highest of (w) the price per share
              --------------
     of Issuer Common Stock at which a Tender Offer or an Exchange Offer
     therefor has been made (other than by Holder), (x) the price per share of
     Issuer Common Stock to be paid by any third party pursuant to an agreement
     with Issuer, (y) the highest closing price for shares of Issuer Common
     Stock within the six-month period immediately preceding the consolidation,
     merger or sale in question and (z) in the event of a sale of all or
     substantially all of Issuer's assets or deposits, an amount equal to (i)
     the sum of the price paid in such sale for such assets (and/or deposits)
     and the current market value of the remaining assets of Issuer, as
     determined by a nationally-recognized investment banking firm selected by
     the Holder and reasonably acceptable to the Issuer, divided by (ii) the
     number of shares of Issuer Common Stock outstanding at such time.  In the
     event that a Tender Offer or an Exchange Offer is made for Issuer Common
     Stock or an agreement is entered into for a merger or consolidation
     involving consideration other than cash, the value of the securities or
     other property issuable or deliverable in exchange for Issuer Common Stock
     shall be determined

                                      -7-
<PAGE>

     by a nationally-recognized investment banking firm selected by Holder and
     reasonably acceptable to the Issuer.

        (4)  "Average Price" shall mean the average closing price of a share of
              -------------
     Substitute Common Stock for the one year immediately preceding the
     consolidation, merger or sale in question, but in no event higher than the
     closing price of the shares of Substitute Common Stock on the day preceding
     such consolidation, merger or sale; provided that if Issuer is the issuer
     of the Substitute Option, the Average Price shall be computed with respect
     to a share of common stock issued by Issuer, the person merging into Issuer
     or by any company which controls such person, as Holder may elect.


     (f)  In no event, pursuant to any of the foregoing paragraphs, shall the
Substitute Option be exercisable for more than 19.9% of the aggregate of the
shares of Substitute Common Stock outstanding prior to exercise of the
Substitute Option.  In the event that the Substitute Option would be exercisable
for more than 19.9% of the aggregate of the shares of Substitute Common Stock
but for the limitation in the first sentence of this Section 7(f), Substitute
Option Issuer shall make a cash payment to Holder equal to the excess of (i) the
value of the Substitute Option without giving effect to the limitation in the
first sentence of this Section 7(f) over (ii) the value of the Substitute Option
after giving effect to the limitation in the first sentence of this Section
7(f).  This difference in value shall be determined by a nationally-recognized
investment banking firm selected by Holder and reasonably acceptable to the
Issuer.

     (g)  Issuer shall not enter into any transaction described in Section 7(b)
unless the Acquiring Corporation and any person that controls the Acquiring
Corporation assume in writing all the obligations of Issuer hereunder and take
all other actions that may be necessary so that the provisions of this Section 7
are given full force and effect (including, without limitation, any action that
may be necessary so that the holders of the other shares of common stock issued
by Substitute Option Issuer are not entitled to exercise any rights by reason of
the issuance or exercise of the Substitute Option and the shares of Substitute
Common Stock are otherwise in no way distinguishable from or have lesser
economic value (other than any diminution in value resulting from the fact that
the shares of Substitute Common Stock are restricted securities, as defined in
Rule 144 under the Securities Act or any successor provision) than other shares
of common stock issued by Substitute Option Issuer).

     8.  REPURCHASE AT THE OPTION OF HOLDER.

     (a)  At the request of Holder at any time commencing upon the first
occurrence of a Repurchase Event (as defined in Section 8(d)) and ending 12
months immediately thereafter, Issuer shall repurchase from Holder (i) the
Option and (ii) all shares of Issuer Common Stock purchased by Holder pursuant
hereto with respect to which Holder then has beneficial ownership.  The date on
which Holder exercises its rights under this Section 8 is referred to as the

"Request Date."  Such repurchase shall be at an aggregate price (the "Section 8
-------------                                                         ---------
Repurchase Consideration") equal to the sum of:
------------------------


        (i)  the aggregate Purchase Price paid by Holder for any shares of
     Issuer Common Stock acquired pursuant to the Option with respect to which
     Holder then has beneficial ownership;

                                      -8-
<PAGE>

        (ii)  the excess, if any, of (x) the Applicable Price (as defined below)
     for each share of Issuer Common Stock over (y) the Purchase Price (subject
     to adjustment pursuant to Section 7), multiplied by the number of shares of
     Issuer Common Stock with respect to which the Option has not been
     exercised; and

        (iii)  the excess, if any, of the Applicable Price over the Purchase
     Price (subject to adjustment pursuant to Section 7) paid (or, in the case
     of Option Shares with respect to which the Option has been exercised but
     the Closing Date has not occurred, payable) by Holder for each share of
     Issuer Common Stock with respect to which the Option has been exercised and
     with respect to which Holder then has beneficial ownership, multiplied by
     the number of such shares.


     (b)  If Holder exercises its rights under this Section 8, Issuer shall,
within 10 business days after the Request Date, pay the Section 8 Repurchase
Consideration to Holder in immediately available funds, and contemporaneously
with such payment Holder shall surrender to Issuer the Option and the
certificates evidencing the shares of Issuer Common Stock purchased thereunder
with respect to which Holder then has beneficial ownership, and shall warrant
that it has sole record and beneficial ownership of such shares and that the
same are then free and clear of all liens, claims, charges and encumbrances of
any kind whatsoever.  Notwithstanding the foregoing, to the extent that prior
notification to or approval of the Federal Reserve Board, the Federal Deposit
Insurance Corporation, the Massachusetts Division of Banks or any other
Governmental Entity is required in connection with the payment of all or any
portion of the Section 8 Repurchase Consideration, Holder shall have the ongoing
option to revoke its request for repurchase pursuant to Section 8, in whole or
in part, or to require that Issuer deliver from time to time that portion of the
Section 8 Repurchase Consideration that it is not then so prohibited from paying
and promptly file the required notice or application for approval and
expeditiously process the same (and each party shall cooperate with the other in
the filing of any such notice or application and the obtaining of any such
approval).  If the Federal Reserve Board, the Federal Deposit Insurance
Corporation, the Massachusetts Division of Banks or any other Governmental
Entity disapproves of any part of Issuer's proposed repurchase pursuant to this
Section 8, Issuer shall promptly give notice of such fact to Holder.  If the
Federal Reserve Board, the Federal Deposit Insurance Corporation, the
Massachusetts Division of Banks or any other Governmental Entity prohibits the
repurchase in part but not in whole, then Holder shall have the right (i) to
revoke the repurchase request or (ii) to the extent permitted by the Federal
Reserve Board, the Federal Deposit Insurance Corporation, the Massachusetts
Division of Banks or other Governmental Entity, determine whether the repurchase
should apply to the Option and/or Option Shares and to what extent to each, and
Holder shall thereupon have the right to exercise the Option as to the number of
Option Shares for which the Option was exercisable at the Request Date less the
sum of the number of shares covered by the Option in respect of which payment
has been made pursuant to Section 8(a)(ii) and the number of shares covered by
the portion of the Option (if any) that has been repurchased.  Holder shall
notify Issuer of its determination under the preceding sentence within five
business days of receipt of notice of disapproval of the repurchase. The parties
hereto agree that Issuer's obligations to repurchase the Option or Option Shares
under this Section 8 shall terminate upon the occurrence of an Exercise
Termination Event unless a Purchase Event shall have occurred prior to the
occurrence of an Exercise Termination Event.

                                      -9-
<PAGE>

     (c)  For purposes of this Agreement, the "Applicable Price" means the
                                               ----------------
highest of (i) the highest price per share of Issuer Common Stock paid for any
such share by the person or groups described in Section 8(d)(i), (ii) the price
per share of Issuer Common Stock received by holders of Issuer Common Stock in
connection with any merger or other business combination transaction described
in Section 7(b)(i), 7(b)(ii) or 7(b)(iii), or (iii) the highest closing sales
price per share of Issuer Common Stock quoted on the Nasdaq Stock Market's
National Market ("NASDAQ/NMS") (or if Issuer Common Stock is not quoted on
                  ----------
NASDAQ/NMS, the highest bid price per share as quoted on the principal trading
market or securities exchange on which such shares are traded, as reported by a
recognized source chosen by Holder) during the 60 business days preceding the
Request Date; provided, however, that in the event of a sale of less than all of
Issuer's assets, the Applicable Price shall be the sum of the price paid in such
sale for such assets and the current market value of the remaining assets of
Issuer as determined by a nationally-recognized investment banking firm selected
by Holder and reasonably acceptable to the Issuer, divided by the number of
shares of Issuer Common Stock outstanding at the time of such sale.  If the
consideration to be offered, paid or received pursuant to either of the
foregoing clauses (i) or (ii) shall be other than in cash, the value of such
consideration shall be determined in good faith by an independent nationally-
recognized investment banking firm selected by Holder and reasonably acceptable
to Issuer, which determination shall be conclusive for all purposes of this
Option.

     (d)  As used herein, a "Repurchase Event" shall occur if (i) any person
                             ----------------
(other than Grantee or any subsidiary of Grantee) shall have acquired beneficial
ownership of (as such term is defined in Rule 13d-3 promulgated under the
Exchange Act), or the right to acquire beneficial ownership of, or any "group"
                                                                        -----
(as such term is defined in Section 13(d)(3) of the Exchange Act) shall have
been formed which beneficially owns or has the right to acquire beneficial
ownership of, 50% or more of the then outstanding shares of Issuer Common Stock,
or (ii) any of the transactions described in Section 7(b)(i), Section 7(b)(ii)
or Section 7(b)(iii) shall be consummated.

     9.  REGISTRATION RIGHTS.

     (a)  DEMAND REGISTRATION RIGHTS.  Issuer shall, subject to the conditions
of Section 9(c), at the request of Grantee (whether on its own behalf or on
behalf of any subsequent Holder of this Option (or part thereof) or any of the
shares of Issuer Common Stock issued pursuant hereto), as expeditiously as
possible prepare and file a registration statement under the Securities Act if
such registration is necessary in order to permit the sale or other disposition
of any or all shares of Issuer Common Stock or other securities that have been
acquired by or are issuable to Holder upon exercise of the Option in accordance
with the intended method of sale or other disposition stated by Holder in such
request, including without limitation a "shelf" registration statement under
                                         -----
Rule 415 under the Securities Act or any successor provision, and Issuer shall
use its best efforts to qualify such shares or other securities for sale under
any applicable state securities laws.


     (b)  ADDITIONAL REGISTRATION RIGHTS.  If Issuer at any time after the
exercise of the Option proposes to register any shares of Issuer Common Stock
under the Securities Act in connection with an underwritten public offering of
such Issuer Common Stock, Issuer will promptly give written notice to Holder of
its intention to do so and, upon the written request of Holder given within 30
days after receipt of any such notice (which request shall specify the number of
shares of Issuer Common Stock intended to be included in such underwritten
public offering by Holder), Issuer will cause all such shares for which a Holder
shall have requested participation in such registration to be

                                      -10-
<PAGE>

so registered and included in such underwritten public offering; provided,
however, that Issuer may elect to not cause any such shares to be so registered
(i) if the underwriters in good faith object for valid business reasons, or (ii)
in the case of a registration solely to implement an employee benefit plan or a
registration filed on Form S-4 under the Securities Act or any successor form;
provided, further, however, that such election pursuant to clause (i) may only
be made one time. If some but not all the shares of Issuer Common Stock with
respect to which Issuer shall have received requests for registration pursuant
to this Section 9(b) shall be excluded from such registration, Issuer shall make
appropriate allocation of shares to be registered among Holders permitted to
register their shares of Issuer Common Stock in connection with such
registration pro rata in the proportion that the number of shares requested to
be registered by each such Holder bears to the total number of shares requested
to be registered by all such Holders then desiring to have Issuer Common Stock
registered for sale.

     (c)  CONDITIONS TO REQUIRED REGISTRATION.  Issuer shall use all reasonable
efforts to cause each registration statement referred to in Section 9(a) to
become effective and to obtain all consents or waivers of other parties which
are required therefor and to keep such registration statement effective;
provided, however, that Issuer may delay any registration of Option Shares
required pursuant to Section 9(a) for a period not exceeding 90 days if Issuer
shall in good faith determine that any such registration would adversely affect
an offering or contemplated offering of other securities by Issuer, and Issuer
shall not be required to register Option Shares under the Securities Act
pursuant to Section 9(a):


        (i)  prior to the earliest of (A) termination of the Affiliation
     Agreement pursuant to Article XI thereof, and (B) a Purchase Event or a
     Preliminary Purchase Event;

        (ii)  on more than one occasion during any calendar year and on more
     than two occasions in total;

        (iii)  within 90 days after the effective date of a registration
     referred to in Section 9(b) pursuant to which the Holder or Holders
     concerned were afforded the opportunity to register such shares under the
     Securities Act and such shares were registered as requested; and

        (iv)  unless a request therefor is made to Issuer by the Holder or
     Holders of at least 25% or more of the aggregate number of Option Shares
     (including shares of Issuer Common Stock issuable upon exercise of the
     Option) then outstanding.


     In addition to the foregoing, Issuer shall not be required to maintain the
effectiveness of any registration statement after the expiration of nine months
from the effective date of such registration statement.  Issuer shall use all
reasonable efforts to make any filings, and take all steps, under all applicable
state securities laws to the extent necessary to permit the sale or other
disposition of the Option Shares so registered in accordance with the intended
method of distribution for such shares, provided, however, that Issuer shall not
be required to consent to general jurisdiction or to qualify to do business in
any state where it is not otherwise required to so consent to such jurisdiction
or to so qualify to do business. Notwithstanding anything to the contrary
contained herein, in no event shall Issuer be obligated to effect more than two
registrations pursuant to this Section 9 by reason of the fact that there shall
be more than one Holder as a result of any assignment or division of this
Agreement.

                                      -11-
<PAGE>

     (d)  EXPENSES.  Issuer will pay all expenses (including without limitation
registration fees, qualification fees, blue sky fees and expenses, accounting
expenses, legal expenses and printing expenses incurred by it) in connection
with the first registration pursuant to Section 9(a) or (b) and all other
qualifications, notifications or exemptions pursuant to Section 9(a) or (b).
Underwriting discounts and commissions relating to Option Shares, fees and
disbursements of counsel to the Holder(s) of Option Shares being registered and
any other expenses incurred by such Holder(s) in connection with any such
registration shall be borne by such Holder(s).

     (e)  INDEMNIFICATION.  In connection with any registration under Section
9(a) or (b), Issuer hereby indemnifies each Holder, and each underwriter
thereof, including each person, if any, who controls such Holder or underwriter
within the meaning of Section 15 of the Securities Act, against all expenses,
losses, claims, damages and liabilities caused by any untrue, or alleged untrue,
statement of a material fact contained in any registration statement or
prospectus or notification or offering circular (including any amendments or
supplements thereto) or any preliminary prospectus, or caused by any omission,
or alleged omission, to state therein a material fact required to be stated
therein or necessary to make the statements therein not misleading, except
insofar as such expenses, losses, claims, damages or liabilities of such
indemnified party are caused by any untrue statement or alleged untrue statement
that was included by Issuer in any such registration statement or prospectus or
notification or offering circular (including any amendments or supplements
thereto) in reliance upon, and in conformity with, information furnished in
writing to Issuer by such indemnified party expressly for use therein, and
Issuer and each officer, director and controlling person of Issuer shall be
indemnified by such Holder, or by such underwriter, as the case may be, for all
such expenses, losses, claims, damages and liabilities caused by any untrue, or
alleged untrue, statement that was included by Issuer in any such registration
statement or prospectus or notification or offering circular (including any
amendments or supplements thereto) in reliance upon, and in conformity with,
information furnished in writing to Issuer by such Holder or such underwriter,
as the case may be, expressly for such use.

     Promptly upon receipt by a party indemnified under this Section 9(e) of
notice of the commencement of any action against such indemnified party in
respect of which indemnity or reimbursement may be sought against any
indemnifying party under this Section 9(e), such indemnified party shall notify
the indemnifying party in writing of the commencement of such action, but,
except to the extent of any actual prejudice to the indemnifying party, the
failure so to notify the indemnifying party shall not relieve it of any
liability which it may otherwise have to any indemnified party under this
Section 9(e).  In case notice of commencement of any such action shall be given
to the indemnifying party as above provided, the indemnifying party shall be
entitled to participate in and, to the extent it may wish, jointly with any
other indemnifying party similarly notified, to assume the defense of such
action at its own expense, with counsel chosen by it and reasonably satisfactory
to such indemnified party.  The indemnified party shall have the right to employ
separate counsel in any such action and participate in the defense thereof, but
the fees and expenses of such counsel (other than reasonable costs of
investigation) shall be paid by the indemnified party unless (i) the
indemnifying party agrees to pay the same, (ii) the indemnifying party fails to
assume the defense of such action with counsel reasonably satisfactory to the
indemnified party, or (iii) the indemnified party has been advised by counsel
that one or more legal defenses may be available to the indemnifying party that
may be contrary to the interest of the indemnified party, in which case the
indemnifying party shall be entitled to assume the defense of

                                      -12-
<PAGE>

such action notwithstanding its obligation to bear fees and expenses of such
counsel. No indemnifying party shall be liable for any settlement entered into
without its consent, which consent may not be unreasonably withheld.

     If the indemnification provided for in this Section 9(e) is unavailable to
a party otherwise entitled to be indemnified in respect of any expenses, losses,
claims, damages or liabilities referred to herein, then the indemnifying party,
in lieu of indemnifying such party otherwise entitled to be indemnified, shall
contribute to the amount paid or payable by such party to be indemnified as a
result of such expenses, losses, claims, damages or liabilities in such
proportion as is appropriate to reflect the relative benefits received by
Issuer, the selling Holders and the underwriters from the offering of the
securities and also the relative fault of Issuer, the selling Holders and the
underwriters in connection with the statement or omissions which results in such
expenses, losses, claims, damages or liabilities, as well as any other relevant
equitable considerations.  The amount paid or payable by a party as a result of
the expenses, losses, claims, damages and liabilities referred to above shall be
deemed to include any legal or other fees or expenses reasonably incurred by
such party in connection with investigating or defending any action or claim;
provided, however, that in no case shall the selling Holders be responsible, in
the aggregate, for any amount in excess of the net offering proceeds
attributable to its Option Shares included in the offering.  No person guilty of
fraudulent misrepresentation (within the meaning of Section 11(g) of the
Securities Act) shall be entitled to contribution from any person who was not
guilty of such fraudulent misrepresentation.  Any obligation by any Holder to
indemnify shall be several and not joint with other Holders.

     In connection with any registration pursuant to Section 9(a) or (b) above,
Issuer and each selling Holder (other than Grantee) shall enter into an
agreement containing the indemnification provisions of this Section 9(e).

     (f)  MISCELLANEOUS REPORTING.  Issuer shall comply with all reporting
requirements and will do all such other things as may be necessary to permit the
expeditious sale at any time of any Option Shares by the Holder(s) in accordance
with and to the extent permitted by any rule or regulation permitting
nonregistered sales of securities promulgated by the Commission from time to
time, including, without limitation, Rule 144A.  Issuer shall at its expense
provide the Holder with any information necessary in connection with the
completion and filing of any reports or forms required to be filed by them under
the Securities Act or the Exchange Act, or required pursuant to any state
securities laws or the rules of any stock exchange.

     (g)  ISSUE TAXES.  Issuer will pay all stamp taxes in connection with the
issuance and the sale of the Option Shares and in connection with the exercise
of the Option, and will save any Holder harmless, without limitation as to time,
against any and all liabilities, with respect to all such taxes.

     10.  QUOTATION; LISTING.  If Issuer Common Stock or any other securities to
be acquired upon exercise of the Option are then authorized for quotation or
trading or listing on NASDAQ/NMS or any securities exchange, Issuer, upon the
request of Holder, will promptly file an application, if required, to authorize
for quotation or trading or listing the shares of Issuer Common Stock or other
securities to be acquired upon exercise of the Option on NASDAQ/NMS  or such
other securities exchange and will use its best efforts to obtain approval, if
required, of such quotation or listing as soon as practicable.

                                      -13-
<PAGE>

     11.  DIVISION OF OPTION.  Upon the occurrence of a Purchase Event or a
Preliminary Purchase Event, this Agreement (and the Option granted hereby) are
exchangeable, without expense, at the option of Holder, upon presentation and
surrender of this Agreement at the principal office of the Issuer for other
Agreements providing for Options of different denominations entitling the holder
thereof to purchase in the aggregate the same number of shares of Issuer Common
Stock purchasable hereunder.  The terms "Agreement" and "Option" as used herein
                                         ---------       ------
include any other Agreements and related Options for which this Agreement (and
the Option granted hereby) may be exchanged.  Upon receipt by Issuer of evidence
reasonably satisfactory to it of the loss, theft, destruction or mutilation of
this Agreement, and (in the case of loss, theft or destruction) of reasonably
satisfactory indemnification, and upon surrender and cancellation of this
Agreement, if mutilated, Issuer will execute and deliver a new Agreement of like
tenor and date.  Any such new Agreement executed and delivered shall constitute
an additional contractual obligation on the part of Issuer, whether or not the
Agreement so lost, stolen, destroyed or mutilated shall at any time be
enforceable by anyone.

     12.  MISCELLANEOUS.

     (a)  EXPENSES.  Except as otherwise provided in Section 9, each of the
parties hereto shall bear and pay all costs and expenses incurred by it or on
its behalf in connection with the transactions contemplated hereunder, including
fees and expenses of its own financial consultants, investment bankers,
accountants and counsel.

     (b)  WAIVER AND AMENDMENT.  Any provision of this Agreement may be waived
at any time by the party that is entitled to the benefits of such provision.
This Agreement may not be modified, amended, altered or supplemented except upon
the execution and delivery of a written agreement executed by the parties
hereto.

     (c)  ENTIRE AGREEMENT; NO THIRD PARTY BENEFICIARIES; SEVERABILITY.  This
Agreement, together with the Affiliation Agreement and the other documents and
instruments referred to herein and therein, between Grantee and Issuer (i)
constitutes the entire agreement and supersedes all prior agreements and
understandings, both written and oral, between the parties with respect to the
subject matter hereof, and (ii) is not intended to confer upon any person other
than the parties hereto (other than the indemnified parties under Section 9(e)
and any transferee of the Option Shares or any permitted transferee of this
Agreement pursuant to Section 12(h)) any rights or remedies hereunder.  If any
term, provision, covenant or restriction of this Agreement is held by a court of
competent jurisdiction or a federal or state regulatory agency to be invalid,
void or unenforceable, the remainder of the terms, provisions, covenants and
restrictions of this Agreement shall remain in full force and effect and shall
in no way be affected, impaired or invalidated.  If for any reason such court or
regulatory agency determines that the Option does not permit Holder to acquire,
or does not require Issuer to repurchase, the full number of shares of Issuer
Common Stock as provided in Sections 3 and 8 (as adjusted pursuant to Section
7), it is the express intention of Issuer to allow Holder to acquire or to
require Issuer to repurchase such lesser number of shares as may be permissible
without any amendment or modification hereof.

     (d)  GOVERNING LAW.  This Agreement shall be governed and construed in
accordance with the laws of The Commonwealth of Massachusetts without regard to
any applicable conflicts of law rules.

                                      -14-
<PAGE>

     (e)  DESCRIPTIVE HEADINGS.  The descriptive headings contained herein are
for convenience of reference only and shall not affect in any way the meaning or
interpretation of this Agreement.

     (f)  NOTICES.  All notices and other communications hereunder shall be in
writing and shall be deemed given if delivered personally, telecopied (with
confirmation) or sent by overnight mail service or mailed by registered or
certified mail (return receipt requested) postage prepaid, to the parties at the
following address (or at such other address for a party as shall be specified by
like notice):

     If to Grantee:

          100 Old King=s Highway
          Sandwich, Massachusetts 02563
          Attention: President
          Fax: (508) 833-0005

     With required copes to each of :

          Harry K. Kantarian, Esq.
          Leonard S. Volin, Esq.
          Housley Kantarian & Bronstein, P.C.
          1220 19th Street, N.W.
          Suite 700
          Washington, D.C. 29936
          Fax: (202) 822-9611

     If to Grantee, to:

          791 Purchase Street
          New Bedford, Massachusetts  02740-2101
          Attention: President
          Fax:  (508) 984-6212

     With required copies to each of:

          Peter W. Coogan, Esq.
          Carol Hempfling Pratt, Esq.
          Foley, Hoag & Eliot LLP
          One Post Office Square
          Boston, Massachusetts 02109
          Fax: (617) 832-7000

or such other address as shall be furnished in writing by any party, and any
such notice or communication shall be deemed to have been given as of the date
so mailed.

                                      -15-
<PAGE>

     (g)  COUNTERPARTS.  This Agreement and any amendments hereto may be
executed in two counterparts, each of which shall be considered one and the same
agreement and shall become effective when both counterparts have been signed, it
being understood that both parties need not sign the same counterpart.

     (h)  ASSIGNMENT. Neither of the parties hereto may assign any of its rights
or obligations under this Agreement or the Option created hereunder to any other
person, without the express written consent of the other party, except that in
the event a Purchase Event shall have occurred prior to an Exercise Termination
Event, Grantee, subject to the express provisions hereof, may assign in whole or
in part its rights and obligations hereunder;  provided, however, that until the
date 15 days following the date on which the Federal Reserve Board approves an
application by Grantee under the BHCA to acquire the shares of Issuer Common
Stock subject to the Option, Grantee may not assign its rights under the Option
except in (i) a widely dispersed public distribution, (ii) a private placement
in which no one party acquires the right to purchase in excess of 2% of the
voting shares of Issuer, (iii) an assignment to a single party (e.g., a broker
or investment banker) for the purpose of conducting a widely dispersed public
distribution on Grantee's behalf, or (iv) any other manner approved by the
Federal Reserve Board.

     (i)  FURTHER ASSURANCES.  In the event of any exercise of the Option by
Holder, Issuer and Holder shall execute and deliver all other documents and
instruments and take all other action that may be reasonably necessary in order
to consummate the transactions provided for by such exercise.

     (j)  SPECIFIC PERFORMANCE.  The parties hereto agree that this Agreement
may be enforced by either party through specific performance, injunctive relief
and other equitable relief.  Both parties further agree to waive any requirement
for the securing or posting of any bond in connection with the obtaining of any
such equitable relief and that this provision is without prejudice to any other
rights that the parties hereto may have for any failure to perform this
Agreement.

     (k) EXTENSION OF EXERCISE TIME PERIODS FOR REGULATORY COMPLIANCE. The time
periods set forth in this Agreement for the exercise by Grantee or the Holder to
exercise its rights with respect to the Option or a Substitute Option or with
respect to repurchase of the Option shall be extended: (i) to the extent
necessary to obtain all regulatory approvals for the exercise of such rights and
for the expiration of all statutory waiting periods; and (ii) to the extent
necessary to avoid liability under Section 16(b) of the 1934 Act by reason of
such exercise.

                                      -16-
<PAGE>

     IN WITNESS WHEREOF, Issuer and Grantee have caused this Stock Option
Agreement to be signed by their respective officers thereunto duly authorized,
all as of the day and year first written above.


Attest:                                 SANDWICH BANCORP, INC.


/s/ Pamela J. Buttrick                  By:    /s/ Frederic D. Legate
-----------------------------------         ----------------------------------
                                            Name:  Frederic D. Legate
                                            Title: President and Chief
                                                   Executive Officer



                                        THE 1855 BANCORP

Attest:

 /s/ Marilyn H. Parkinson                   By:   /s/ Kevin G. Champagne
------------------------------------           -------------------------------
                                               Name:  Kevin G. Champagne
                                               Title: President and Chief
                                                      Executive Officer

                                      -17-