<PAGE>

                                                                  EXHIBIT 10.61

                                                                  EXECUTION COPY

                               REVISED AND AMENDED
                                 TRUST AGREEMENT

                          Dated as of November 1, 2002

                       and amended as of December 12, 2002

                                      among

                    PLATINUM UNDERWRITERS REINSURANCE, INC.

                                 ("Platinum US")

                                   as Grantor,

                        MOUNTAIN RIDGE INSURANCE COMPANY

                               ("Mountain Ridge")

                                as Beneficiary,

                                       and

                       STATE STREET BANK AND TRUST COMPANY

                                   As Trustee

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
PARTIES                                                                                             PAGE
<S>               <C>                                                                               <C>
Section 1.        Creation and Deposit of Assets to the Trust Account..............................   2

Section 2.        Withdrawal of Assets from the Trust Account......................................   5

Section 3.        Application of Assets............................................................   6

Section 4.        Redemption, Investment and Substitution of Assets................................   8

Section 5.        The Income Account...............................................................   9

Section 6.        Right to Vote Assets.............................................................   9

Section 7.        Additional Rights and Duties of the Trustee......................................   9

Section 8.        The Trustee's Compensation, Expenses and Indemnification.........................  13

Section 9.        Resignation or Removal of the Trustee............................................  14

Section 10.       Termination of the Trust Account.................................................  15

Section 11.       Insolvency of Grantor............................................................  16

Section 12.       Definitions......................................................................  17

Section 13.       Governing Law....................................................................  18

Section 14.       Grantor's Tax Status.............................................................  19

Section 15.       Successors and Assigns...........................................................  19

Section 16.       Severability.....................................................................  19

Section 17.       Entire Agreement.................................................................  19

Section 18.       Amendments.......................................................................  20

Section 19.       Notices, etc.....................................................................  20

Section 20.       Headings.........................................................................  21

Section 21.       Counterparts.....................................................................  21
</TABLE>

EXHIBIT A        Form of 100% Quota Share Retrocession Agreement
EXHIBIT B        List of Assets Deposited to the Trust Account

                                      -ii-

<PAGE>

                       REVISED AND AMENDED TRUST AGREEMENT

                  REVISED AND AMENDED TRUST AGREEMENT, dated as of November 1,
2002 and amended as of December 12, 2002 (the "Agreement"), among PLATINUM
UNDERWRITERS REINSURANCE, INC. ("Platinum US"), a Maryland-domiciled insurance
company (the "Grantor"), MOUNTAIN RIDGE INSURANCE COMPANY ("Mountain Ridge"), a
Minnesota-domiciled insurance company (the "Beneficiary"), and STATE STREET BANK
AND TRUST COMPANY, a Massachusetts trust company (the "Trustee") (the Grantor,
the Beneficiary and the Trustee are hereinafter each sometimes referred to
individually as a "Party" and collectively as the "Parties").

                               W I T N E S S E T H

                  WHEREAS, the Grantor and the Beneficiary have entered into
three 100% Quota Share Retrocession Agreements, copies of which are attached as
Exhibit A hereto (the "Retrocession Agreements");

                  WHEREAS, the Beneficiary desires the Grantor to secure
payments of all amounts at any time and from time to time owing by the Grantor
to the Beneficiary under or in connection with the Retrocession Agreements;

                  WHEREAS, the Grantor desires to transfer to the Trustee for
deposit to a trust account (the "Trust Account") assets in order to secure
payments by the Grantor under or in connection with the Retrocession Agreements;

                  WHEREAS, the Trustee has agreed to act as trustee hereunder,
and to hold such assets in trust in the Trust Account for the sole use and
benefit of the Beneficiary; and

                                       -1-

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                  WHEREAS, this Agreement is established for the sole use and
benefit of the Beneficiary and for the purposes of setting forth the duties and
powers of the Trustee with respect to the Trust Account and the relative rights
and obligations of the Parties hereto;

                  NOW, THEREFORE, for consideration of the premises and for
other good and valuable consideration, the receipt of which is hereby
acknowledged, the Parties hereby agree as follows:

SECTION 1.        CREATION AND DEPOSIT OF ASSETS TO THE TRUST ACCOUNT.

                  (a)      The Grantor shall establish and maintain the Trust
Account for the benefit of the Beneficiary as security for the obligations of
the Grantor under the Retrocession Agreements. The Grantor shall ensure that the
Trust Account shall be in a form reasonably satisfactory to the Beneficiary and,
except as otherwise expressly provided herein, shall comply in all material
respects with the requirements under Maryland Insurance Law applicable to trust
funds established for credit for reinsurance purposes. The Trustee shall
administer the Trust Account in its name as Trustee for the Beneficiary. The
Trust Account shall be subject to withdrawal by the Beneficiary solely as
provided herein.

                  (b)      (i)     On the date hereof, the Grantor shall deposit
Qualifying Assets into the Trust Account equal to all payments and proceeds
received by the Grantor as Initial Section A Premium and Initial Section B
Premium (in each case as defined in the Retrocession Agreements) in respect of
all Reinsurance Contracts (as defined in the Retrocession Agreements). The list
of assets so deposited is set forth on Exhibit B hereto, as amended from time to
time. In addition, Grantor shall deposit Qualifying Assets into the Trust
Account equal to all payments received by Grantor under Sections 4.01(b) and
4.02(b) of the Retrocession Agreements, if any, following determination of the
Final Section A Premium and Final Section B

                                      -2-

<PAGE>

Premium or the Arbitrated Final Section A Premium and/or the Arbitrated Final
Section B Premium, as the case may be (each as defined in the Retrocession
Agreements). All assets received in the Trust Account are hereinafter referred
to as "Assets".

                  (ii)     As of the end of each calendar quarter, the Grantor
shall calculate the fair market value of the Assets held in the Trust Account as
of the last day of such quarter (such amount, the "Ending Asset Value") and the
aggregate loss, loss adjustment expense reserves, unearned premium reserves,
ceding commission and other reserves related to the Reinsurance Contracts as
reported in the statutory financial statements filed by the Grantor with the
Maryland Insurance Administration, as of the last day of such quarter (the
"Ending Reserves") and shall provide such calculation to the Beneficiary within
five days of the filing of such statutory financial statements with the Maryland
Insurance Administration. Calculation of the Ending Reserves shall exclude the
aggregate loss, loss adjustment expense reserves, unearned premium reserves,
ceding commission and other reserves related to any Reinsurance Contract
underwritten by the manager in accordance with the terms of Article III(a) of
the Underwriting Management Agreement between Beneficiary and Grantor, as
manager, dated as of the date hereof ("New Business").

                  (iii)    The Ending Reserves, calculated so as to exclude
reserves with respect to New Business, as provided in Section l(b)(ii) hereof,
shall be reduced by any increase in reserves during such calendar quarter due to
reserve strengthening or adverse development in the reserves recognized by the
Grantor in its statutory financial statements during such calendar quarter (as
so reduced, the "Adjusted Ending Reserves"). The excess of the Adjusted Ending
Reserves over the Ending Asset Value, if any, shall be the "Excess Reserves". To
the extent the Adjusted Ending Reserves exceed the Ending Asset Value, the
Grantor promptly shall deposit in

                                      -3-

<PAGE>

the Trust Account sufficient Qualifying Assets with a fair market value equal to
such excess. For the avoidance of doubt, it is understood that to the extent
such excess is due to adverse development with respect to the related reserves,
Grantor shall not be required to make any additional deposit of Qualifying
Assets into the Trust Account. To the extent the Ending Asset Value exceeds the
Adjusted Ending Reserves, the Grantor may withdraw Assets with a fair market
value equal to the amount of such excess.

                  (c)      Upon receipt of the quarterly calculation from the
Grantor, the Beneficiary shall have the right to reasonably object to such
calculation and to offer a reasonable proposal for the amount of the reserves
described in Section 1(b) hereof. If the parties in good faith are not able to
resolve the disagreement within two weeks of the Beneficiary's indication of
disagreement, the parties shall mutually agree upon an independent actuarial
firm to determine an appropriate level of aggregate reserves as described in
Section 1(b) hereof with respect to the Reinsurance Contracts, such level to be
no more than the amount proposed by the Beneficiary and no less than the amount
reported by the Grantor, and both parties agree to be bound by such
determination. The fees and expenses of the actuarial firm shall be shared
equally by the Grantor and the Beneficiary.

                  (d)      The Grantor shall retain the investment discretion
with respect to the Assets in the Trust Account, provided, however, that all
Assets held in the Trust Account shall be invested consistently with the
Investment Guidelines (the "Investment Guidelines") attached to the
Discretionary Investment Advisory Agreement dated as of November 4, 2002, by and
between Alliance Capital Management L.P. and the Grantor.

                                      -4-

<PAGE>

                  (e)      The Grantor shall be permitted to liquidate the trust
at the earlier of (i) such time as the Trustee receives notice from the Grantor
and the Beneficiary that the Grantor's obligations under all of the Retrocession
Agreements have been met or are terminated or waived or (ii) such time as the
Trustee receives notice from the Grantor that the Adjusted Ending Reserves so
reported by the Grantor do not exceed $10 million as of two successive calendar
year ends. In such event, the Trustee shall, within 10 days, transfer to the
Grantor any Assets remaining in the Trust Account.

                  (f)      The Beneficiary shall bear the costs and expenses of
the Trustee.

                  (g)      The Trustee shall have no responsibility to determine
(i) whether the Assets in the Trust Account are sufficient to secure the
Grantor's liabilities under the Retrocession Agreements, (ii) whether they
represent Qualifying Assets or (iii) whether any investment of Assets in the
Trust Account as directed by the Grantor complies with the Investment
Guidelines. Further, the Trustee shall have no responsibility whatsoever to
determine whether the Assets in the Trust Account entitle either the Grantor or
the Beneficiary to favorable or unfavorable tax accounting, or other treatment,
consideration, evaluation or calculation under any law, rule or regulation.

SECTION 2.        WITHDRAWAL OF ASSETS FROM THE TRUST ACCOUNT,

                  (a)      Without notice to the Grantor, the Beneficiary shall
have the right, at any time and from time to time, notwithstanding anything to
the contrary contained in the Retrocession Agreements, to withdraw from the
Trust Account, upon written notice to the Trustee (the "Withdrawal Notice"),
such Assets as are specified in such Withdrawal Notice. The Beneficiary need
present no statement or document in addition to a Withdrawal Notice in order

                                       -5-

<PAGE>

to withdraw any Assets; nor is said right of withdrawal or any other provision
of this Agreement subject to any conditions or qualifications not contained in
this Agreement.

                  (b)      Upon receipt of a Withdrawal Notice, the Trustee
shall promptly take the steps necessary to transfer absolutely all right, title
and interest in the Assets specified in such Withdrawal Notice and shall deliver
physical custody of such Assets to or for the account of the Beneficiary. In the
event that the Trustee must sell an investment in order to comply with the
Withdrawal Notice, the Trustee shall not be liable for any loss or penalty
associated with such investment, except to the extent such loss or penalty
arises from the Trustee's negligence, willful misconduct or lack of good faith,
or failure to comply with the Withdrawal Notice.

                  (c)      Subject to paragraph (a) of this Section 2 and to
Section 4 of this Agreement, in the absence of a Withdrawal Notice, the Trustee
shall allow no substitution or withdrawal of any Asset from the Trust Account.

                  (d)      The Trustee shall have no responsibility whatsoever
to determine that any Assets withdrawn from the Trust Account pursuant to this
Section 2 are withdrawn in compliance with the Retrocession Agreements, or will
be used and applied in the manner contemplated by Section 3 of this Agreement.

SECTION 3.        APPLICATION OF ASSETS.

                  (a)      The Beneficiary hereby covenants to the Grantor that
it shall use and apply any withdrawn Assets, without diminution because of the
insolvency of the Beneficiary or the Grantor, for the following purposes only:

                                       -6-

<PAGE>

                  (i)      to pay or reimburse the Beneficiary for the Grantor's
share under the Retrocession Agreements regarding any losses and allocated loss
expenses paid by the Beneficiary but not recovered from the Grantor, and
unearned premiums due to the Beneficiary if not otherwise paid by the Grantor,
or for other amounts due to the Beneficiary, if not otherwise paid by the
Grantor, in accordance with the terms of the Retrocession Agreements;

                  (ii)     to make payment to the Grantor of any amounts held in
the Trust Account that exceed 100% of the actual amount required to fund the
Grantor's entire Obligations (as hereinafter defined), and

                  (iii)    except in the event of a liquidation of the trust
under Section l(e) hereof, where the Beneficiary has received a Termination
Notice (as hereinafter defined) pursuant to Section 10 of this Agreement and
where all or a portion of the Grantor's Obligations remain unliquidated and
undischarged ten days prior to the Termination Date (as hereinafter defined), to
withdraw amounts equal to such Obligations and deposit such amounts in a
separate account, in the name of the Beneficiary, in any Qualified United States
Financial Institution (as defined herein), apart from its other assets, in trust
for the uses and purposes specified in subparagraphs (i) and (ii) of this
Section as may remain executory after such withdrawal and for any period after
such Termination Date. For the purposes of this subparagraph (iii), the phrase
"the Trust Account" in subparagraph (ii) of this Section shall be deemed to read
"the separate account" established pursuant to this subparagraph (iii),

                  (iv)     For purposes of this Section 3, all Assets shall be
valued at their current fair market value.

                                       -7-

<PAGE>

SECTION 4.        REDEMPTION, INVESTMENT AND SUBSTITUTION OF ASSETS.

                  (a)      The Trustee shall surrender for payment all maturing
Assets and all Assets called for redemption (and provide written notice to the
Beneficiary to that effect) and deposit the principal amount of the proceeds of
any such payment into the Trust Account.

                  (b)      From time to time, at the written order and direction
of the Grantor, any instruction or order concerning investments being referred
to herein as an "Investment Order", the Trustee shall invest the Trust Account
in Qualifying Assets.

                  (c)      From time to time, the Grantor may, subject to the
written approval of the Beneficiary as provided in Section 4(d) hereof, direct
the Trustee to substitute Qualifying Assets for other Qualifying Assets held in
the Trust Account at such time. The Trustee shall have no responsibility
whatsoever to determine the value of such substituted securities or that such
substituted securities constitute Qualifying Assets.

                  (d)      Subject to the terms of Section 5, the Trustee shall
not allow any substitutions or withdrawals of Assets from the Trust Account,
except on (i) written approval from the Beneficiary, or (ii) a call on or the
maturity of any Assets in the Trust Account if the Trustee pays the proceeds
from the Asset into the Trust Account.

                  (e)      All investments and substitutions of securities
referred to in paragraphs (b) and (c) of this Section 4 shall be in compliance
with the relevant limitations in "Qualifying Assets", as set forth in Section 11
of this Agreement. The Trustee shall have no responsibility whatsoever to
determine that any Assets in the Trust Account are or continue to be Qualifying
Assets. The Trustee shall execute Investment Orders and settle securities
transactions by itself or by means of an agent or broker. The Trustee shall not
be responsible for any act or omission, or

                                      -8-

<PAGE>

for the solvency, of any such agent or broker unless said act or omission is the
result, in whole or in part, of the Trustee's negligence, willful misconduct or
lack of good faith.

                  (f)      Any loss incurred from any investment pursuant to the
terms of this Section 4 shall be borne exclusively by the Trust Account. The
Trustee shall not be liable for any loss due to changes in market rates or
penalties for early redemption.

SECTION 5.        THE INCOME ACCOUNT.

                  The Grantor shall establish and maintain an income account
with the Trustee for its own benefit (the "Income Account") at an office of the
Trustee. All payments of interest and dividends actually received in respect of
Assets in the Trust Account shall be deposited and held in the Income Account
and distributed by the Trustee to the Grantor within 10 days following the end
of each calendar month. The Grantor shall provide the Trustee with the
appropriate wiring instructions for such distributions.

SECTION 6.        RIGHT TO VOTE ASSETS.

                  (a)      The Trustee shall forward all annual and interim
stockholder reports and all proxies and proxy materials relating to the Assets
in the Trust Account to the Grantor. The Grantor shall have the full and
unqualified right to vote any Assets in the Trust Account.

 SECTION 7.       ADDITIONAL RIGHTS AND DUTIES OF THE TRUSTEE.

                  (a)      The Trustee shall receive Assets and hold the Assets
in a safe place;

                  (b)      The Trustee shall determine that the Assets are in a
form that the Beneficiary, or the Trustee on direction of the Beneficiary, may
negotiate whenever necessary, without consent or signature from the Grantor or
any other person or entity;

                                      -9-

<PAGE>

                  (c)      The Trustee shall provide to the Grantor and the
Beneficiary a statement of all Assets in the Trust Account on its inception and
following the end of each month;

                  (d)      The Trustee shall notify the Grantor and the
Beneficiary, within 10 days, of any deposits to or withdrawals from the Trust
Account;

                  (e)      The Trustee shall hold the Assets in the Trust
Account;

                  (f)      The Trustee may deposit any Assets in the Trust
Account in a book-entry account maintained at the appropriate Federal Reserve
Bank or in depositories such as the Depository Trust Company. Assets may be held
in the name of a nominee maintained by the Trustee or by any such depository.

                  (g)      The Trustee shall accept and open all mail directed
to the Grantor or the Beneficiary in care of the Trustee.

                  (h)      Upon the request of the Grantor or the Beneficiary,
the Trustee shall promptly permit the Grantor or the Beneficiary, their
respective agents, employees or independent auditors to examine, audit, excerpt
transcribe and copy, during the Trustee's normal business hours, any books,
documents, papers and records relating to the Trust Account or the Assets.

                  (i)      The Trustee is authorized to follow and rely upon all
instructions given by applicable officers named in incumbency certificates
furnished to the Trustee from time to time by the Grantor and Beneficiary,
respectively, and by attorneys-in-fact acting under written authority furnished
to the Trustee by the Grantor or the Beneficiary, including, without limitation,
instructions given by letter, facsimile transmission, telegram, teletype,
cablegram or

                                      -10-

<PAGE>

electronic media other than e-mail, if the Trustee believes such instructions to
be genuine and to have been signed, sent or presented by the proper party or
parties. Such instructions may also be in a tested communication or in a
communication utilizing access codes effected between electro-mechanical or
electronic devices. The Trustee shall not incur any liability to anyone
resulting from actions taken by the Trustee in reliance in good faith on such
instructions. The Trustee shall not incur any liability in executing
instructions (i) from an attorney-in-fact or (ii) from any officer of the
Grantor of the Beneficiary named in an incumbency certificate delivered
hereunder prior to receipt by it of a more current certificate.

                  (j)      The duties and obligations of the Trustee shall only
be such as are specifically set forth in this Agreement, as it may from time to
time be amended, and no implied duties or obligations shall be read into this
Agreement against the Trustee. The Trustee shall not be charged with knowledge
of any document, instrument or agreement, other than this Agreement. The Trustee
shall only be liable for its own negligence, willful misconduct or lack of good
faith.

                  (k)      No provision of this Agreement shall require the
Trustee to take any action which, in the Trustee's reasonable judgment, would
result in any violation of this Agreement or any provision of law or, following
written advice from counsel, expose the Trustee to personal liability.

                  (l)      The Trustee may confer with counsel of its own choice
in relation to matters arising under this Agreement and shall have full and
complete authorization from the other Parties hereunder for any action taken or
suffered by it under this Agreement or under any transaction contemplated hereby
in good faith and in accordance with opinion of such counsel.

                                      -11-

<PAGE>

                  (m)      The invasion of the trust corpus to pay compensation
to, or reimburse the expense of, the Trustee is hereby prohibited.

                  (n)      The Trustee shall deliver to the Beneficiary written
notice of termination as and when required under Section 10(b).

                  (o)      Except as may arise from the Trustee's own negligence
or willful misconduct or lack of good faith, the Trustee shall be without
liability for any loss, liability, claim or expense resulting from or caused by
events or circumstances beyond the reasonable control of the Trustee, including,
without limitation, the interruption, suspension or restriction of trading on or
the closure of any securities markets, power or other mechanical or
technological failures or interruptions, or computer viruses or communications
disruptions, work stoppages, natural disasters or other similar events or acts,
delays or inability to perform its duties due to any disorder in market
infrastructure with respect to any particular security or changes to any
provision of any present or future law or regulation or order of the United
States of America, or any state thereof, or any other country, or political
subdivision thereof or any court of competent jurisdiction.

                  (p)      The Trustee, in incurring any debt, liability or
obligation, or in taking or omitting to take any action for or in connection
with the Trust, is and shall be deemed to be acting solely as a trustee, and not
in an individual capacity. The Trustee shall assume no responsibility and shall
not be held to any personal liability whatsoever in tort, contract, or otherwise
for any action taken or omitted pursuant to this Agreement. In the event that
the Grantor or the Beneficiary enters into any agreement or arrangement of any
kind with any third party with respect to all or any part of the Trust Account,
the Grantor or the Beneficiary, as

                                      -12-

<PAGE>

appropriate, shall ensure that the agreement or arrangement shall pose no risk
of personal liability to the Trustee.

SECTION 8.        THE TRUSTEE'S COMPENSATION, EXPENSES AND INDEMNIFICATION.

                  (a)      The Beneficiary shall pay the Trustee, as
compensation for its services under this Agreement, a fee at rates determined by
the Trustee and agreed to by the Beneficiary, from time to time and communicated
in writing to the Beneficiary. The Beneficiary shall pay or reimburse the
Trustee for all of the Trustee's reasonable expenses and disbursements in
connection with its duties under this Agreement (including attorney's fees and
expenses), except any such expense, or disbursement as may arise from the
Trustee's negligence, willful misconduct or lack of good faith. The Grantor
shall indemnify, defend and save harmless the Trustee from all loss or expense
(including attorney's fees and expenses) arising out of or in connection with
(i) its execution and performance of this Agreement, except to the extent that
such loss, liability or expense is due to the negligence, willful misconduct or
lack of good faith of the Trustee, or (ii) its following any instructions or
other directions from the Grantor, except to the extent that its following any
such instructions or direction is expressly forbidden by the terms hereof. In no
event shall the Trustee be liable for special, indirect or consequential loss or
damage of any kind whatsoever. The Grantor hereby acknowledges that the
foregoing indemnities shall survive the resignation of the Trustee or the
termination of this Agreement and hereby grants the Trustee a lien, right of
set-off and security interest in the funds in the Income Account for the payment
of any claim for indemnity, or payment of its fees and reasonable expenses and
disbursements, as expressly provided in this Section 8. In the event that the
Trustee should withdraw funds from the Income Account in satisfaction of its
fees, expenses or

                                      -13-

<PAGE>

disbursements pursuant to this Section 8, the Beneficiary shall be liable to,
and shall reimburse, the Grantor for such amounts.

                  (b)      No Assets shall be withdrawn from the Trust Account
or used in any manner for paying compensation to, or reimbursement or
indemnification of, the Trustee.

SECTION 9.        RESIGNATION OR REMOVAL OF THE TRUSTEE.

                  (a)      The Trustee may resign at any time by giving not less
than sixty (60) days' written notice thereof to the Beneficiary and to the
Grantor, such resignation to become effective only on the acceptance of
appointment by a successor trustee and the transfer to such successor trustee of
all Assets in the Trust Account in accordance with paragraph (b) of this
Section 9.

                  (b)      Upon receipt of the Trustee's notice of resignation,
the Grantor and the Beneficiary shall appoint a successor trustee. Any successor
trustee shall be a Qualified United States Financial Institution and shall not
be a Parent, a Subsidiary or an Affiliate of the Grantor or the Beneficiary.
Upon the acceptance of the appointment as trustee hereunder by a successor
trustee and the transfer to such successor trustee of all Assets in the Trust
Account, the resignation of the Trustee shall become effective. Thereupon, such
successor trustee shall succeed to and become vested with all the rights,
powers, privileges and duties of the Trustee, and the Trustee shall be
discharged from any future duties and obligations under this Agreement, but the
Trustee shall continue after its resignation to be entitled to the benefits of
the indemnities provided herein for the Trustee. If a successor has not been
appointed within sixty (60) days of the Trustee's notice of resignation, the
Trustee may apply to a court of competent jurisdiction to have a successor
trustee appointed.

                                      -14-

<PAGE>

                  (c)      The Grantor may remove the Trustee at any time by
giving not less than sixty (60) days' written notice thereof to the Beneficiary
and to the Trustee, such removal to become effective only on the acceptance of
appointment by a successor trustee and the transfer to such successor trustee of
all Assets in the Trust Account in accordance with paragraph (d) of this Section
9.

                  (d)      Upon receipt of the Grantor's notice of removal, the
Grantor and the Beneficiary shall appoint a successor trustee. Any successor
trustee shall be a Qualified United States Financial Institution and shall not
be a Parent, a Subsidiary or an Affiliate of the Grantor or the Beneficiary.
Upon the acceptance of the appointment as trustee hereunder by a successor
trustee and the transfer to such successor trustee of all Assets in the Trust
Account, the removal of the Trustee shall become effective. Thereupon, such
successor trustee shall succeed to and become vested with all the rights,
powers, privileges and duties of the Trustee, and the Trustee shall be
discharged from any future duties and obligations under this Agreement, but the
Trustee shall continue after its removal to be entitled to the benefits of the
indemnities provided herein for the Trustee.

SECTION 10.       TERMINATION OF THE TRUST ACCOUNT.

                  (a)      The Trust Account and this Agreement, except as
provided in Section 1(e) hereof and except for the indemnities provided herein,
may be terminated only after (i) the Grantor and the Beneficiary have given the
Trustee written notice of their intention to terminate the Trust Account (the
"Notice of Intention"), and (ii) the Trustee has given the Grantor and the
Beneficiary the written notice specified in paragraph (b) of this Section 10.
The Notice of Intention shall specify the date on which the notifying Party
intends the Trust Account to terminate (the "Proposed Date").

                                      -15-

<PAGE>

                  (b)      Within ten Business Days following receipt by the
Trustee of the Notice of Intention, the Trustee shall give written notification
(the "Termination Notice") to the Beneficiary and the Grantor of the date (the
"Termination Date") on which the Trust Account shall terminate. The Termination
Date shall be (a) the Proposed Date (or if not a Business Day, the next Business
Day thereafter), if the Proposed Date is at least 30 days but no more than 45
days subsequent to the date the Termination Notice is given; (b) 30 days
subsequent to the date the Termination Notice is given (or if not a Business
Day, the next Business Day thereafter), if the Proposed Date is fewer than 30
days subsequent to the date the Termination Notice is given; or (c) 45 days
subsequent to the date the Termination Notice is given (or if not a Business
Day, the next Business Day thereafter), if the Proposed Date is more than 45
days subsequent to the date the Termination Notice is given.

                  (c)      On the Termination Date, upon receipt of written
approval of the Beneficiary, the Trustee shall transfer to the Grantor any
Assets remaining in the Trust Account, at which time all liability of the
Trustee with respect to such Assets shall cease.

SECTION 11.       INSOLVENCY OF GRANTOR.

                  (a)      Notwithstanding any other provision in this
Agreement, if the Grantor has been declared insolvent or placed into
receivership, rehabilitation, liquidation, or similar proceedings under the laws
of Maryland, the Trustee shall comply with any order of the regulatory authority
with oversight over the Trust Account or court of competent jurisdiction
directing the Trustee to transfer to such regulatory authority or other
designated receiver all of the Assets in the Trust Account, less any amounts
owed by the Grantor to the Trustee pursuant to this Agreement.

                                      -16-

<PAGE>

                  (b)      The Assets so transferred shall be applied in
accordance with the priority statutes of the state in which the Trust Account is
established applicable to the assets of insurance companies in liquidation.

                  (c)      If the regulatory authority with oversight over the
Trust Account determines that the Assets held in the Trust Account or any part
of the Assets are not necessary to satisfy the claims of the Beneficiary, the
Assets or any part of the Assets shall be returned to the Trustee for
distribution in accordance with this Agreement.

SECTION 12.       DEFINITIONS.

                  Except as the context shall otherwise require, the following
terms shall have the following meanings for all purposes of this Agreement (the
definitions to be applicable to both the singular and the plural forms of each
term defined if both such forms of such term are used in this Agreement):

                  The term "Affiliate" with respect to any corporation shall
mean a corporation which directly, or indirectly through one of more
intermediaries, controls or is controlled by, or is under common control with,
such corporation. The term "control" (including the related terms "controlled
by" and "under common control with") shall mean the ownership, directly or
indirectly, of more than fifty percent (50%) of the voting stock of a
corporation.

                  The term "Business Day" shall mean any day on which the
offices of the Trustee in Boston, Massachusetts are open for business.

                  The term "Expenses" shall mean the Trustee's reasonable
expenses and disbursements in connection with its duties under this Agreement
(including reasonable

                                      -17-

<PAGE>

attorney's fees and expenses) not including any such expense, or disbursement as
may arise from the Trustee's gross negligence, willful misconduct or lack of
good faith.
                  The term "Obligations" shall mean, with respect to the
Retrocession Agreement, (a) reinsured losses and allocated loss expenses paid by
the Beneficiary, but not recovered from the Grantor, (b) reserves for reinsured
losses reported and outstanding, (c) reserves for reinsured losses incurred but
not reported, and (d) reserves for allocated reinsured loss expenses and
unearned premiums.

                  The term "Parent" shall mean an institution that, directly or
indirectly, controls another institution.

                  The term "person" shall mean and include an individual, a
corporation, a partnership, an association, a trust, an unincorporated
organization or a government or political subdivision thereof.

                  The term "Qualified United States Financial Institution" shall
have the meaning provided in COMAR 31.05.08.08.

                  The term "Qualifying Assets" shall mean and include any
security that conforms with the criteria set forth in the Investment Guidelines.

                  The term "Subsidiary" shall mean an institution controlled,
directly or indirectly, by another institution.

SECTION 13.       GOVERNING LAW.

                  This Agreement shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts without regard to
its choice of laws principles.

                                      -18-

<PAGE>

SECTION 14.       GRANTOR'S TAX STATUS.
                  The Grantor shall provide the Trustee with a Certificate of
Foreign Status on Form W-8 (or any successor form) or its Tax Identification
Number (TIC) as assigned by the Internal Revenue Service, as applicable. All
income arising from the Assets in the Trust Account shall be treated as income
of the Grantor for U.S. federal income tax purposes.

SECTION 15.       SUCCESSORS AND ASSIGNS.

                  No Party may assign this Agreement or any of its obligations
hereunder without the prior written consent of the other Parties; provided,
however, that this Agreement shall inure to the benefit of and bind those who,
by operation of law, become successors to the Parties, including, without
limitation, any liquidator, rehabilitator, receiver or conservator and any
successor merged or consolidated entity and provided further that, in the case
of the Trustee, the successor trustee is eligible to be a trustee under the
terms hereof.

SECTION 16.       SEVERABILITY.

                  In the event that any provision of the Agreement shall be
declared invalid or unenforceable by any regulatory body or court having
jurisdiction, such invalidity or unenforceability shall not affect the validity
or enforceability of the remaining portions of this Agreement.

SECTION 17.       ENTIRE AGREEMENT.

                 This Agreement constitutes the entire agreement among the
Parties, and there are no understandings or agreement, conditions or
qualifications relative to this Agreement which are not fully expressed in this
Agreement.

                                      -19-

<PAGE>

SECTION 18.       AMENDMENTS.

                  This Agreement may be modified or otherwise amended, and the
observance of any term of this Agreement may be waived, if such modification,
amendment or waiver is in writing and signed by all of the Parties.

SECTION 19.       NOTICES, ETC.

                  Unless otherwise provided in this Agreement, all notices,
directions, requests, demands, acknowledgments and other communications required
or permitted to be given or made under the terms hereof shall be in writing and
shall be deemed to have been duly given or made on the date received when
addressed as follows:

                 If to the Grantor:      Platinum Underwriters Reinsurance, Inc.
                                         195 Broadway
                                         New York, New York 10007
                                         Attention: Chief Financial Officer
                                         Fax No.: (212) 238-9202

                 If to the Beneficiary:  The St. Paul Companies, Inc.
                                         385 Washington Street
                                         St. Paul,Minnesota 55102
                                         Attention: General Counsel
                                         Fax No.: (410)205-6967

                 If to the Trustee:      State Street Bank and Trust Company
                                         801 Pennsylvania Avenue
                                         Kansas City, Missouri 64105
                                         Attention: Vice President
                                         Fax No.: (816)871-9210

                  Each Party may from time to time designate a different address
for notices, directions, requests, demands, acknowledgments and other
communications by giving written notice of such change to the other Parties. All
notices, directions, requests, demands, acknowledgments and other communications
relating to the Beneficiary's approval of the

                                      -20-

<PAGE>

Grantor's authorization to substitute Assets and to the termination of the Trust
Account shall be in writing and may not be made or given by prepaid telex,
telegraph or telecopier.

SECTION 20.       HEADINGS.

                  The headings of the Sections and the Table of Contents have
been inserted for convenience of reference only, and shall not be deemed to
constitute a part of this Agreement.

SECTION 21.       COUNTERPARTS.

                  This Agreement may be executed in any number of counterparts,
each of which when so executed and delivered shall constitute an original, but
such counterparts together shall constitute one and the same Agreement.

                  [THIS SPACE INTENTIONALLY LEFT BLANK]

                                      -21-

<PAGE>

                  IN WITNESS WHEREOF, the Parties hereto have caused this
Agreement to be executed and delivered by their respective officers thereunto
duly authorized as of the date first above written,

                                    PLATINUM UNDERWRITERS REINSURANCE, INC.
                                    As Grantor

                                    By: /s/ Michael D. Price
                                        -----------------------------------
                                        Name: Michael D. Price
                                        Title:

                                    MOUNTAIN RIDGE INSURANCE COMPANY
                                    As Beneficiary

                                    By: /s/ Thomas A. Bradley
                                        -----------------------------------
                                        Name:  Thomas A. Bradley
                                        Title: Executive Vice President and
                                               Chief Financial Officer

                                        and

                                    STATE STREET BANK AND TRUST COMPANY
                                    As Trustee

                                    By: /s/ Kenneth A. Bergeron
                                        -----------------------------------
                                        Name:  Kenneth A. Bergeron
                                        Title: Senior Vice President


                                      -22-

<PAGE>

                                    EXHIBIT A

1.       100% Quota Share Retrocession Agreement (Non-Traditional - D-1), dated
         as of November 1,2002

2.       100% Quota Share Retrocession Agreement (Non-Traditional - D-2), dated
         as of November 1,2002

3.       100% Quota Share Retrocession Agreement (Non-Traditional - D-Stop
         Loss), Dated as of November 1,2002

<PAGE>

                                    EXHIBIT B

                            List of Assets Deposited
                              to the Trust Account

                                      Cash