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                                                                   Exhibit 10.23

                   ONEBEACON'S 2004 MANAGEMENT INCENTIVE PLAN

PURPOSE
The Management Incentive Plan (MIP) is an integral part of the total
compensation program for senior Home Office and Field Office management. Its
primary purpose is to focus attention on 2004 profitability goals and to reward
eligible participants for the achievement of those goals.

ELIGIBILITY
The Plan is limited to home office and field office senior staff who have a
significant impact on OneBeacon's operating results.

TARGET AWARDS
Target awards for all participants, expressed as a percent of salary, will be
set and approved by the Board of OneBeacon Corporation.

PERFORMANCE MEASURE
The Corporate MIP pool will be established based upon achievement of a 94%
combined ratio for total OneBeacon operations, computed on an adjusted calendar
year basis. This measurement will be used to establish a pool of money to be
allocated to business units and Home Office departments. At a corporate combined
ratio of 94%, the plan will fund an amount equal the sum of each of the plan's
participant's potential award at their target bonus percentage. The OneBeacon
Board of Directors may adjust the size of the pool based on under or over
achievement of the company's target combined ratio and the following objectives:
     -   Successful integration of Atlantic Mutual's commercial business into
         OneBeacon and the achievement of real growth and efficiencies in
         commercial lines.
     -   Successful deployment of our new personal insurance products and
         technology
     -   Continued profitable growth of our specialty businesses, including
         AutoOne and Skylands
     -   Continued claims savings and improved quality

INDIVIDUAL AWARDS
Each business unit will be judged against a number of metrics including, where
appropriate, a combined ratio result target, agreed to in advance with the
President of OneBeacon. Generally these targets will relate to the aggregate
financial plan rolled up by branch and line of business, but the targets will
not always match the plan (in many cases, the targets are more aggressive). If
the combined ratio target is achieved, in conjunction with other business
metrics, the business may be awarded 100% of its indicated share of the
corporate pool. Businesses failing to reach target may or may not, at the
discretion of the President, receive a reduced, partial allocation of the pool.
Businesses exceeding objectives may receive greater than 100% of indicated
allocation. In no event will the sum of the performance adjusted business unit
pools be greater than the performance adjusted company pool.

Within each business, it will be the prerogative of the business leader, with
guidance from and after consultation with the company President, to further
allocate the business's pool amount to the constituent branches, lines of
business and individuals, based upon performance against targets established
within the business. It will be the responsibility of the business leader, with

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guidance from the President, to establish appropriate targets for the
constituent branches, lines of business, departments, or individuals at the
outset of the MIP year.

For corporate or administrative functions that support all or multiple regions
or businesses, MIP individuals will receive allocations from the corporate pool
based upon attainment of their department and individual MIP goals for 2004.

Review and evaluation of performance will be conducted during the first quarter
following the end of the plan year. Incentive payments will be paid once plan
year results have been produced and evaluated.

The salary used to determine the amount of the individual awards will be that in
effect at the end of the plan year (12/31/04).

PLAN PARTICIPATION FOR NEW HIRES
Employees hired during the plan year are eligible to participate in the MIP.
Awards will be pro-rated specifically based on date of hire.

SPECIAL CIRCUMSTANCES
The OneBeacon Board of Directors may, in its sole discretion, also recognize
extraordinary conditions or circumstances in determining payment levels.

In the event of voluntary termination during a plan year or prior to the payment
of awards, other than retirement at the end of the plan year, no incentive
payment will be made. In the event of death or disability, the plan participant
or beneficiary may be considered for a partial award payment.

EFFECT ON BENEFIT PLANS
Amounts paid under the terms of this plan will not be counted for purposes of
determining compensation under any employee benefit plan sponsored by OneBeacon.

PLAN CONTINUATION
Notwithstanding any of the aforementioned, the plan may be amended or
terminated, in whole or in part, at any time, by the Board of Directors.

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                                                                   Exhibit 10.26

                    This AMENDED AND RESTATED REVENUE SHARING AGREEMENT (this
               "AGREEMENT") is made and entered into as of the date of the
               Acquisition (as defined below) as amended as of January 1, 2003,
               between and among Fund American Companies, Inc., a Delaware
               corporation (the "ACQUISITION COMPANY"), Folksamerica Reinsurance
               Company, a New York reinsurance company ("FOLKSAMERICA"), and
               JOHN D. GILLESPIE, an individual resident of the State of
               Connecticut (the "INVESTMENT MANAGER").

          WHEREAS the Acquisition Company and the Investment Manager desire to
enter into an agreement under which (i) the Acquisition Company and the
Investment Manager shall share the revenue of Prospector Partners, L.L.C.
("PROSPECTOR PARTNERS"), and Prospector Associates, L.L.C. ("PROSPECTOR
ASSOCIATES"), and (ii) the Acquisition Company shall pay the expenses of
Prospector Partners during the Agreement Term (as defined below); and

          WHEREAS Folksamerica and the Investment Manager desire to enter into
an agreement under which Folksamerica shall receive a founder's revenue share
(the "FOUNDER'S REVENUE SHARE") in respect of revenue of certain businesses of
the Investment Manager as provided herein.

          NOW, THEREFORE, in consideration of the mutual covenants contained
herein and intending to be legally bound hereby, the parties hereto hereby agree
as follows:

          SECTION 1. TERM. The Acquisition Company's responsibility for the
expenses of Prospector Partners and the sharing of the revenue of Prospector
Partners and Prospector Associates by the Acquisition Company under the terms of
Sections 2, 3, 4 and 5 hereof shall commence on January 1, 2001 (the
"COMMENCEMENT DATE"), and shall remain in effect until any written notice of
termination of the separate agreement between the Acquisition Company and John
D. Gillespie (the "SEPARATE AGREEMENT"), dated as of the date of the Acquisition
Company's acquisition (the "ACQUISITION") of CGU Corporation, a Delaware
corporation, shall be given as required under Section 2 thereof; provided,
however, that the provisions of Sections 2, 3, 4 and 5 of this Agreement shall
not take effect unless and until the Separate Agreement shall take effect. With
respect to the provisions of Sections 2, 3, 4 and 5 of this Agreement, the
period of time between the Commencement Date and the termination of such
provisions pursuant to the terms of this Agreement is herein referred to as the
"AGREEMENT TERM".

          SECTION 2. SHARING OF REVENUE. (a) The Investment Manager shall (i)
pay or cause to be paid to the Acquisition Company out of any amounts allocable
to him from the gross revenue of Prospector Partners and Prospector Associates
in respect of each calendar year, no later than 30 days after the issuance of
audited financial statements for Prospector Partners Fund, L.P., Prospector
Partners Small Cap Fund, L.P., and Prospector Offshore Fund (Bermuda), Ltd., and
any other fund that the Investment Manager shall be actively involved in the
investment management during the Agreement Term (hereinafter any such funds
shall collectively be

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referred to as the "FUNDS" and individually referred to as a "FUND"), in respect
of such year, or, at his discretion, (ii) cause to be allocated, as of the last
day of such year, to any capital account of the Acquisition Company in any of
the Funds out of amounts otherwise allocable to any of the Investment Manager's
capital accounts in any of the Funds in respect of such year, or (iii) shall
pay, cause to be paid and/or cause to be so allocated, in aggregate, the
"Applicable Percentage" (as defined below) of the Net Revenue (as defined below)
in respect of such year to the extent such amount shall not have been previously
paid or so allocated. Notwithstanding any provision herein to the contrary, the
Investment Manager may pay or cause to be paid to the Acquisition Company, at
any time in any calendar year during the Agreement Term, the Acquisition
Company's share, or any portion of its share, of the Net Revenue for such year
on an estimated basis. If the total amount paid to the Acquisition Company under
this paragraph (a) in respect of any year shall exceed the Acquisition Company's
share of Net Revenue for such year as finally determined, the Acquisition
Company shall return such excess to the Investment Manager within 30 days of
such final determination. The "Applicable Percentage" shall be 50%; provided,
however, that with respect to any year or portion of a year in which Kevin
O'Brien is an employee of Prospector Partners, L.L.C., the Applicable Percentage
shall be 33%. "NET REVENUE" shall be calculated annually on a calendar year
basis and shall mean the sum of (i) the aggregate gross revenue earned by
Prospector Associates and Prospector Partners during any such year in respect of
the Funds, less 24% of any such gross revenue in excess of $500,000 (which 24%
represents the aggregate shares of such gross revenue of the founding investors
of the Funds), and (ii) gross revenue earned by Prospector Partners during such
year in respect of accounts managed by Prospector Partners during the Agreement
Term that are not accounts of any Fund (hereinafter any such accounts shall be
referred to collectively as the "SEPARATE ACCOUNTS" and individually as a
"SEPARATE ACCOUNT"). Notwithstanding anything in the foregoing provisions of
this paragraph to the contrary, the aforementioned definition of Net Revenue
shall not include, (a) with respect to each share of convertible preferred stock
in White Mountains Insurance Group, Ltd., a Bermuda company ("WHITE MOUNTAINS"),
offered in connection with the Acquisition and subscribed to by any Fund or
Separate Account prior to the Acquisition, the excess of $319 over the per share
value at the time of subscription, as determined pursuant to the agreement under
which such shares shall have been subscribed to, (b)(i) any amounts or interests
earned or accrued prior to the Commencement Date, including amounts or interests
earned but not yet paid in respect of Prospector Offshore Fund (Bermuda), Ltd.,
and any investment earnings in respect thereof, and (ii) the Investment
Manager's pro rata share of investment earnings in respect of amounts earned or
accrued, but not yet paid, subsequent to the Commencement Date in respect of
Prospector Offshore Fund (Bermuda), Ltd., and (c) any amounts or interests
earned in respect of any capital account in any of the Funds, or any Separate
Account, owned by the Investment Manager, any member of Prospector Associates or
Prospector Partners and any of the Investment Manager's, or any such member's,
immediate family members or related entities.

          (b) Additionally, during the Agreement Term, the Investment Manager
shall pay or cause to be paid to the Acquisition Company 25% of his allocable
share of the amount that the aggregate cumulative distributions paid to the
Connecticut Fund Business Entities (as hereinafter defined) shall exceed $3
million during the Agreement Term. Such 25% shall be calculated and paid
annually on a calendar year basis no later than 30 days after the issuance of
audited financial

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statements for such entities in respect of each calendar year during the
Agreement Term. The "CONNECTICUT FUND BUSINESS" shall mean the business
activities of the Connecticut Fund Business Entities (as hereinafter defined) in
respect of investments under the Connecticut Insurance Reinvestment Act No.
97-292. The "CONNECTICUT FUND BUSINESS ENTITIES" shall include: (i) Insurance
Capital Partners, LLC; (ii) Olmstead Capital Partners, LLC; (iii) Prospector
Capital Management, LLC; (iv) Prospector Partners CT Fund Investment Management,
LLC; and (v) Prospector Capital Management II, LLC.

          SECTION 3. EXPENSES. In consideration of the Investment Manager
agreeing to the terms of Section 2 hereof, during the Agreement Term the
Acquisition Company shall be responsible for, and shall pay or cause to be paid
on a timely basis, all expenses of Prospector Partners including, but not
limited to, (a) employee compensation (including salaries, incentive bonuses and
employee benefits), other than the Investment Manager's compensation, (b) rents,
(c) any costs associated with relocating the business office, including
leasehold improvements, purchases of office equipment, and furniture,
furnishings and fixtures and (d) any expenses incurred in connection with the
operations of Prospector Partners. The Acquisition Company and the Investment
Manager understand that Prospector Partners expects to hire one or more
additional employees with superior talent and credentials in investment
management activities, and such other support employees as the Investment
Manager deems advisable, and that the salary and any incentive bonus of any such
employee, including any share of Net Revenue of any such employee hired to
conduct investment management activities, shall be included as part of the
expenses the Acquisition Company agrees to pay hereunder.

          SECTION 4. ADDITIONAL INVESTMENTS BY THE ACQUISITION COMPANY. (a) The
Acquisition Company, or any wholly owned affiliate or affiliates of the
Acquisition Company or White Mountains, shall make capital contributions to any
Fund or Separate Account to replace any capital committed to such Fund or
Separate Account as of the date of the public announcement by either the
Acquisition Company or the Investment Manager, or by White Mountains, of the
services to be performed by the Investment Manager pursuant to the Separate
Agreement that shall be withdrawn from such Fund or Separate Account prior to
the second anniversary of the date of such public announcement, in each case as
a result of the Investment Manager committing to provide such services. Any
withdrawal of such committed capital made after the first anniversary and prior
to the second anniversary of such date shall be considered to have been made as
a result of the Investment Manager committing to provide such services if the
individual or entity making such withdrawal shall confirm in writing that such
withdrawal shall have been a result of such commitment.

          (b) If, during the Agreement Term, the Acquisition Company or any of
its affiliates shall desire to place any amount not under the investment
management of Prospector Partners on the Commencement Date under the investment
management of Prospector Partners, such amount shall not be invested in any of
the Funds (other than as an allocation of the Acquisition Company's share of Net
Revenue as provided in paragraph (a) of Section 2 hereof or as a replacement of
withdrawn capital as provided in the foregoing paragraph of this Section 4) but
a Separate Account shall be created by Prospector Partners for each such amount
under the same terms and conditions of the 1% fee paying Separate Accounts
existing on the Commencement Date.

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          SECTION 5. PAYMENT UPON TERMINATION. Following the conclusion of the
Agreement Term, the Acquisition Company (i) shall be entitled to any payment or
allocation pursuant to and under the terms of paragraph (a) of Section 2 hereof
that shall not yet have been paid or allocated but that the Acquisition Company
shall have been entitled to if the Agreement Term had continued until the end of
the year in which such termination shall have occurred, and (ii) shall pay or
cause to be paid on a timely basis all expenses of Prospector Partners that
shall have accrued prior to the conclusion of the Agreement Term but that shall
not yet have been paid.

          SECTION 6. TERMINATION; SURVIVAL. The provisions of Sections 2, 3, 4
and 5 of this Agreement shall terminate upon the giving of written notice of
termination of the Separate Agreement by either party thereto, as required under
Section 2 thereof. The provisions of Section 7 of this Agreement shall terminate
upon the mutual written consent of Folksamerica and the Investment Manager.
Notwithstanding the foregoing, Sections 5 and 8 of this Agreement shall survive
the termination of any provisions of this Agreement.

          SECTION 7. PAYMENT OF FOUNDER'S REVENUE SHARE. (a) The Investment
Manager shall pay the Founder's Revenue Share (if any) in respect of each
calendar year to Folksamerica, no later than 30 days after the issuance of
audited financial statements for Prospector Partners Fund, L.P., Prospector
Partners Small Cap Fund, L.P., and Prospector Offshore Fund (Bermuda), Ltd.
(hereinafter such funds shall collectively be referred to as the "ORIGINAL
FUNDS"). The Founder's Revenue Share in respect of any calendar year shall be
the amount (if any) equal to the Founder's Revenue Share Percentage (as defined
below) multiplied by the excess (if any) of (i) the sum of the gross revenues of
Prospector Partners and of Prospector Associates in respect of such year to the
extent such revenues are allocable to one or more of the Original Funds (and not
allocable to a separately managed account or other investment management
activity) over (ii) Five hundred thousand (500,000).

          (b) The "FOUNDER'S REVENUE SHARE PERCENTAGE" shall initially be six
percent (6%). If Folksamerica withdraws all or any part of its original
$10,000,000.00 investment in the Funds (including a withdrawal of all or any
part of earnings and/or appreciation in respect of such original investment),
the Founder's Revenue Share Percentage or a segregated portion thereof, as
determined below, shall be reduced by the amount equal to one-third of the
Founder's Revenue Share Percentage or the segregated portion thereof, as the
case may be, at the time of such withdrawal per year for each year beginning
with the calendar year of withdrawal until the Founder's Revenue Share
Percentage or segregated portion thereof, as the case may be, shall be reduced
to zero. For purposes of the preceding sentence, in the event Folksamerica
withdraws less than all of its original $10,000,000.00 investment in the Funds
(including a withdrawal of less than all the earnings and/or appreciation in
respect of such original investment) only that portion of the Founder's Revenue
Share Percentage that bears the same ratio to the entire Founder's Revenue Share
Percentage as the amount of the withdrawal bears to the total investment of
Folksamerica at the time of such withdrawal (including earnings and appreciation
thereon) shall be subject to reduction as provided by the foregoing provisions
of this paragraph (b), and the Founder's Revenue Share Percentage shall be
divided and segregated for purposes of identifying the portion thereof subject
to reduction. The Founder's Revenue Share Percentage shall be reduced from time
to time to take into account any reduction in the Founder's Revenue

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Share Percentage and/or any segregated portion thereof pursuant to the
provisions of this paragraph.

          SECTION 8. MISCELLANEOUS. (a) This Agreement shall inure to the
benefit of (i) the Investment Manager and his executors, administrators, heirs,
personal representatives and permitted assigns, (ii) the Acquisition Company and
its successors and permitted assigns and (iii) Folksamerica and its successors
and permitted assigns; provided, however, that except as provided herein, the
Investment Manager shall not be entitled to assign or delegate any of his rights
or obligations in respect of Sections 2, 4 and 5 hereunder without the prior
written consent of the Acquisition Company or his rights or obligations in
respect of Section 7 hereunder without the prior written consent of
Folksamerica; and each of the Acquisition Company and Folksamerica shall be
permitted to assign its interests and obligations under this agreement to any
wholly owned affiliate of the Acquisition Company or White Mountains at anytime
with the prior written consent of the Investment Manager, such consent not to be
unreasonable withheld.

          (b) This Agreement shall be deemed to be made in, and in all respects
shall be interpreted, construed and governed by and in accordance with, the laws
of the State of New York, without regard to the conflicts of law principles of
such State. No provision of this Agreement or any related document shall be
construed against or interpreted to the disadvantage of any party hereto by any
court or other governmental or judicial authority by reason of such party having
or being deemed to have structured or drafted such provision.

          (c) This Agreement constitutes the entire agreement between and among
the Acquisition Company, Folksamerica and the Investment Manager with respect to
the responsibility for the expenses of Prospector Partners, the sharing of
revenue of Prospector Partners and Prospector Associates by the Acquisition
Company and the Investment Manager, and the payment of the Founder's Revenue
Share and, effective as of the Commencement Date, supersedes all prior
agreements, if any, whether written or oral, between and among the Acquisition
Company, Folksamerica and the Investment Manager with respect to such matters.

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be duly executed as of the day and year first above written.

                                   /s/ FUND AMERICAN COMPANIES, INC.

                                   /s/ FOLKSAMERICA REINSURANCE
                                   COMPANY

                                   /s/ JOHN D. GILLESPIE

                                   Prospector Partners, L.L.C., as to the
                                   provisions of Sections 2, 3, 4 and 7 hereof:
                                   /s/ PROSPECTOR PARTNERS, L.L.C.,

                                   Prospector Associates, L.L.C., as to the

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                                   provisions of paragraph (a) of Section 2 and
                                   Section 7 hereof:
                                   /s/ PROSPECTOR ASSOCIATES, L.L.C.,

                                   Each Connecticut Fund Business Entity as to
                                   the provisions of paragraph (b) of Section 2
                                   hereof:
                                   /s/ INSURANCE CAPITAL PARTNERS, LLC

                                   /s/ OLMSTEAD CAPITAL PARTNERS, LLC,

                                   /s/ PROSPECTOR CAPITAL MANAGEMENT, LLC.

                                   /s/ PROSPECTOR PARTNERS CT FUND
                                   INVESTMENT MANAGEMENT, LLC,

                                   /s/ PROSPECTOR CAPITAL
                                   MANAGEMENT II, LLC

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