Document:

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                                                                   Exhibit 10.24

                               FIRST AMENDMENT TO
                               SUB-LEASE AGREEMENT
               CLOVERLEAF COLD STORAGE CO. - THE TITAN CORPORATION

         THIS AGREEMENT is entered into effective as of February 1, 2001. It
amends that certain sub-lease agreement (the "Sub-Lease") entered into effective
as of September 1, 1999, by and between CLOVERLEAF COLD STORAGE CO., an Iowa
corporation ("Landlord"), whose address for the purpose of this Agreement is
2800 Cloverleaf Court, Sioux City, Iowa 51111, and THE TITAN CORPORATION, a
Delaware corporation ("Tenant"), whose address for the purpose of this Agreement
is 3033 Science Park Road, San Diego, California 92121.

         IN CONSIDERATION of the mutual covenants contained in this agreement,
the parties agree to amend the Sub-Lease as follows:

I.   Section 2. of the Sub-Lease is amended to read as follows:

     2.   TERM. The term of this Sub-Lease shall be for twenty (20) years,
          commencing on the Commencement Date and shall expire at midnight on
          the day preceding the 20th anniversary of the Commencement Date unless
          sooner terminated as herein provided.

     A.   COMMENCEMENT DATE: The parties agree that the Commencement Date shall
          be February 1, 2000. The Commencement Date shall constitute the
          commencement of the term of this Sub-Lease for all purposes, whether
          or not Tenant has actually taken possession. If Tenant takes
          possession of the Demised Premises prior to the Commencement Date,
          Tenant shall pay, in advance, additional rental, pro-rated on a per
          diem basis. Tenant's entry into the Demised Premises to perform
          Tenant's work on installing its equipment shall not be deemed to
          constitute taking possession, if such entry occurs before the
          Completion Date.

     B.   OPTION TO REDUCE TERM OF SUB-LEASE. If this Sub-Lease shall be in
          force and effect on the day preceding the 10th anniversary of the
          Commencement Date Date (the "Early Termination Date") and Tenant on
          such date shall have fully performed all of its obligations hereunder,
          and if Tenant is not in default under any terms of this Sub-Lease,
          Tenant shall have the option to reduce the term of this Sub-Lease to
          ten (10) years, so that it would expire at midnight on the Early
          Termination Date. Tenant must provide Landlord with written notice of
          its intent to exercise this option at least 180 days prior to the
          Early Termination Date. If said option is exercised, Tenant shall
          continue to timely pay all amounts due under this Sub-Lease through
          the day preceding the Early Termination Date and in addition, complete
          and pay in full for the removal of Special Buildout Improvements as
          required by Section 29 of this Sub-Lease on or before the day
          preceding the Early Termination Date. Failure to do so shall
          constitute a default by Tenant.

<PAGE>

II.  Section 4 of the Sub-Lease is amended to read as follows:

     4.   RENTAL.

     A.   BASIC RENTAL. Tenant shall pay annual Basic Rental at the rates
          provided below in equal monthly installments, in advance, with the
          first installment due on the Commencement Date, and subsequent
          installments due on the first day of each and every month thereafter,
          at the corporate mailing address of Landlord, 2800 Cloverleaf Court,
          Sioux City, IA 51111 or at such other places as Landlord may designate
          in writing. Said basic rental is subject to increase based upon the
          fluctuation of the Consumer Price Index as set forth hereinafter.

          Such annual Basic Rental shall be fixed for the first year of the
          Sub-Lease term, but shall be adjusted annually thereafter for the
          remainder of the Sub-Lease term. Said adjustment for the first year
          shall be effective beginning on the first anniversary of the
          Commencement Date, with an adjustment for each succeeding year of the
          Sub-Lease term being made on each succeeding anniversary of the
          Commencement Date. The adjustments shall reflect and compensate
          Landlord annually for decreases in the purchasing power of money, if
          any, as measured by the current Consumer Price Index as more
          specifically described below. In no event will the rental be less than
          that of the preceding year. A detailed formula of the annual
          adjustment of rent as aforesaid is specifically set out hereinafter:

          "BASIC RENTAL" for the leased square footage shall be the sum of the
          annual square foot rental rates indicated below multiplied by the
          leased square footage for each type of space, for the entire Demised
          Premises.

<TABLE>
<CAPTION>

               Type of Space                      Square Footage                     Annual Rate
               <S>                                <C>                                <C>
               Office                             4,839 sq. ft.                      $10.50/sq. ft.
               Rest of Demised Premises           14,560 SQ. FT.                     $17.50/sq. ft.
                                                  --------------
               Total Square Footage               19,399 sq. ft.

</TABLE>

          The initial Base Rental shall be $25,467.00 per month ($305,610.00 per
          year)

          "BASE INDEX" shall mean the October 1998 level of the "Consumer Price
          Index - Urban Wage Earners & Clerical Workers (CPI-W) - All Items -
          U.S. City Average (1982-84 = 100)", as published by the Bureau of
          Labor Statistics, U.S. Department of Labor.

          "CURRENT INDEX" shall mean the level of the same index published for
          the month of October of each year prior to the commencement of each
          applicable annual adjustment term.

          "ADJUSTED RENTAL" shall be the adjusted annual square foot Basic
          Rental produced by multiplying the BASIC RENTAL by the ratio of the
          CURRENT INDEX to the BASE INDEX, i.e.:

          ADJUSTED RENTAL = BASIC RENTAL x (CURRENT INDEX/BASE INDEX)

     B.   SPECIAL BUILDOUT RENTAL: In addition to Basic Rental, Tenant shall pay
          to Landlord Special Buildout Rental. Special Buildout Rental shall be
          charged for

<PAGE>

         Landlord provided Tenant Improvements, specifically: (1) the
         construction of the containment room and other buildout within the main
         production room (including but not limited to the maintenance office,
         control room, dosimetry lab, etc.); (2) construction of the office and
         interior buildout to Tenant's specifications (including, but not
         limited to, telephone, data and alarm cabling), but only to the extent
         such costs exceed an allowance of $261,306; and (3) expediting
         expenses.

          In consideration of the actual costs of Tenant Improvements provided
          by Landlord and previously audited by Tenant, Special Buildout Rental
          shall be a monthly amount of $40,850 beginning on the Commencement
          Date through and including the month of January 2001, and thereafter
          the Special Buildout Rental shall be a monthly amount of $24,582
          beginning February 1, 2001 through and including the month of January
          2010. However, notwithstanding anything to the contrary in the
          Sub-Lease, as amended, if the Tenant vacates the premises prior to the
          Early Termination Date, the Special Buildout Rental for the remaining
          months through the Early Termination Date shall become immediately due
          and payable.

     C.   RESTORATION & OTHER AMOUNTS. In addition to the Basic Rental and
          Special Buildout Rental, Tenant shall pay to Landlord the amounts
          provided in Section 29 and all other amounts provided for under the
          other terms of this Sub-Lease. All amounts payable under this
          Sub-Lease shall be deemed rent for all purposes, including default and
          collection.

     E.   Any rental or other payments not paid within 20 days of the due date
          as stated herein shall bear interest of 12% per annum.

     All other provisions of the Sub-Lease shall remain in full force and
     effect.

     CLOVERLEAF COLD STORAGE CO.                 THE TITAN CORPORATION

                                                       /s/ L.L. Fowler
     ---------------------------------           -------------------------------
     Daniel F. Kaplan                            L.L. Fowler
     Vice President & Secretary                  Vice President

STATE OF IOWA              )

COUNTY OF WOODBURY )

On _______________, 2001, before me, the undersigned, a Notary Public in and for
said State, personally came Daniel F. Kaplan, to me personally known to be the
Vice President and Secretary of said Cloverleaf Cold Storage Co., who is
personally known to me to be the identical person whose name is affixed to the
foregoing agreement, and acknowledged the execution thereof to be his voluntary
act and deed as such officer and the voluntary act and deed of said corporation.

                                                 --------------------------
                                                 Notary Public

Attach California All-Purpose Acknowledgement of signature by L.L. Fowler<PAGE>

                                                                     Exhibit 4.5

                             AMENDED AND RESTATED

                         REGISTRATION RIGHTS AGREEMENT

                                     AMONG

                              MARKEL CORPORATION

                             MARKEL HOLDINGS INC.

                                      AND

                       DLJ INTERNATIONAL PARTNERS, C.V.
                          DLJ OFFSHORE PARTNERS, C.V.
                         DLJMB OVERSEAS PARTNERS, C.V.
                      DLJ MERCHANT BANKING FUNDING, INC.
                              DLJ FIRST ESC, L.P.
              DONALDSON, LUFKIN & JENRETTE SECURITIES CORPORATION

                                      AND

                        MARSH & MCLENNAN CAPITAL, INC.

                                      AND

                                 JOHN J. BYRNE

                         Dated as of January 28, 2000
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                  PAGE
                                                                                                  ----
<S>                                                                                               <C>
SECTION 1.  Definitions........................................................................      2
SECTION 2.  Registration under Securities Act..................................................      4
SECTION 3.  Other Registration Rights..........................................................     17
SECTION 4.  Markel Guarantee...................................................................     17
SECTION 5.  Amendments and Waivers.............................................................     17
SECTION 6.  Notices............................................................................     17
SECTION 7.  Binding Agreement..................................................................     18
SECTION 8.  Descriptive Headings...............................................................     19
SECTION 9.  Specific Performance...............................................................     19
SECTION 10.  Effectiveness.....................................................................     19
SECTION 11.  Termination.......................................................................     19
SECTION 12.  Governing Law.....................................................................     19
SECTION 13.  Counterparts......................................................................     19
SECTION 14.  Entire Agreement..................................................................     19
</TABLE>
<PAGE>

                             AMENDED AND RESTATED
                         REGISTRATION RIGHTS AGREEMENT

         This REGISTRATION RIGHTS AGREEMENT is made as of August 15, 1999, as
amended and restated as of January 28, 2000, by and among MARKEL CORPORATION, a
Virginia corporation ("Markel"), MARKEL HOLDINGS INC., a Virginia corporation
(the "Company"), DLJ INTERNATIONAL PARTNERS, C.V., a Netherlands Antilles
limited partnership, DLJ OFFSHORE PARTNERS, C.V., a Netherlands Antilles limited
partnership, DLJMB OVERSEAS PARTNERS, C.V., a Netherlands Antilles limited
partnership, DLJ MERCHANT BANKING FUNDING, INC., a Delaware corporation, DLJ
FIRST ESC, L.P., a Delaware limited partnership and DONALDSON, LUFKIN & JENRETTE
SECURITIES CORPORATION, a Delaware corporation (collectively, the "DLJ
Entities"), MARSH & MCLENNAN CAPITAL, INC., a Delaware corporation, on behalf of
itself and/or MARSH & MCLENNAN RISK CAPITAL HOLDINGS, LTD., a Delaware
corporation, other related Marsh & McLennan Capital, Inc. entities and/or RISK
CAPITAL REINSURANCE COMPANY, a Nebraska domiciled insurance company
(collectively, "Marsh") and JOHN J. BYRNE, on his own behalf and on behalf of
certain entities as to which, with respect to Common Shares held by such
entities, he has voting and dispositive power ("Byrne").

         A        On August 15, 1999, Markel and Terra Nova (Bermuda) Holdings
Ltd., a Bermuda corporation ("TNA"), entered into an Agreement and Plan of
Merger and Scheme of Arrangement, which was subsequently amended on December 10,
1999 and January 28, 2000 (as so amended, the "Merger Agreement").

         B        The Merger Agreement provides for (i) the merger (the
"Merger") of Markel Holdings Sub Ltd., a corporation organized under the laws of
Virginia and a wholly-owned subsidiary of the Company, with and into Markel and
(ii) a Scheme of Arrangement between TNA and certain of its shareholders (the
"Scheme"). Pursuant to the Merger Agreement, each holder of an ordinary share of
TNA will receive in the Merger $13.00 in cash, .07027 ordinary shares of the
Company, no par value (the "Common Shares"), and .07027 of a contingent value
right (a "CVR"), and will become shareholders of the Company. Each CVR will
grant the holder thereof, subject to certain exceptions, the right to receive,
on the date that is 30 months following consummation of the Merger and the
Scheme, the amount, if any, by which $185 exceeds the greater of (i) the average
trading price of a Common Share, calculated as set forth in the Agreement and
(ii) $140. Upon consummation of the Merger and the Scheme, TNA and Markel will
be wholly-owned subsidiaries of the Company, which, at such time, will change
its name to Markel Corporation.
<PAGE>

         C        TNA and the DLJ Entities are parties to that certain
Registration Rights Agreement dated as of March 25, 1996, among TNA and certain
of its stockholders, pursuant to which such stockholders were accorded certain
registration rights with respect to the ordinary shares of TNA held by them (the
"TNA Registration Rights Agreement").

         D        The parties hereto now desire to amend and restate the
Registration Rights Agreement dated as of August 15, 1999 in its entirety.

         In consideration of the parties entering into the agreements and
carrying out the transactions herein described, and for other good and valuable
consideration, the parties agree as follows:

         Section 1. Definitions. As used herein, unless the context otherwise
requires, the following terms have the following respective meanings:

         "Affiliate" means, with respect to any Person, any other Person
directly or indirectly controlling, controlled by, or under common control with
such Person; provided that no stockholder of the Company shall be deemed an
Affiliate of any other stockholder of the Company solely by reason of any
investment in the Company. For the purpose of this definition, the term
"control" (including with correlative meanings, the terms "controlling",
"controlled by" and "under common control with"), when used with respect to any
Person, means the possession, directly or indirectly, of the power to direct or
cause the direction of the management and policies of such Person, whether
through the ownership of voting securities, by contract or otherwise.

         "Board" means the Board of Directors of the Company.

         "Commission" means the Securities and Exchange Commission or any other
United States agency at the time administering the Securities Act.

         "Contingent Value Rights Agreement" means that certain Contingent Value
Rights Agreement relating to the CVRs between the parties listed on the
signature pages thereto, as such agreement may be subsequently amended or
supplemented by the parties thereto.

         "Exchange Act" means the Securities Exchange Act of 1934, or any
similar United States statute, and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time.

         "Person" means an individual, a partnership, a joint venture, a
corporation, a limited liability company, a trust, an unincorporated
organization and a government or any department or agency thereof.

                                       2
<PAGE>

         "Permitted Transferee" means, in the case of any DLJ Entity, (A) any
other DLJ Entity, (B) any general or limited partner of any DLJ Entity (a "DLJ
Partner"), and any corporation, partnership, Affiliated Employee Benefit Trust
or other entity that is an Affiliate of any DLJ Partner (collectively, the "DLJ
Affiliates"), (C) any managing director, general partner, director, limited
partner, officer or employee of Donaldson, Lufkin & Jenrette, Inc. or any entity
controlled by Donaldson, Lufkin & Jenrette, Inc., or the heirs, executors,
administrators, testamentary trustees, legatees or beneficiaries of any of the
foregoing persons referred to in this clause (C) (collectively, "DLJ
Associates"), (D) a trust, the beneficiaries of which, or a corporation, limited
liability company or partnership, the stockholders, members or general or
limited partners of which, include only DLJ Entities, DLJ Affiliates, DLJ
Associates, their spouses or their lineal descendants or (E) a voting trustee
for one or more DLJ Entities, DLJ Affiliates or DLJ Associates under the terms
of a voting trust designated to conform with the requirements of the Insurance
Law of the State of New York.

         "Registrable Securities" means (i) any outstanding Common Shares held
by any Stockholder, (ii) any outstanding CVRs held by any Stockholder and (iii)
any securities issued with respect to any such Common Shares or CVRs by way of
stock dividend or stock split. As to any particular Registrable Securities, such
securities shall cease to be Registrable Securities (i) when a registration
statement with respect to the sale of such securities shall have become
effective under the Securities Act and such securities shall have been
distributed in accordance with such registration statement, (ii) when such
securities have been distributed to the public pursuant to Rule 144 (or any
successor provision) under the Securities Act, (iii) when such securities shall
have been otherwise transferred, except as contemplated by Section 7 of this
Agreement, or (iv) when such securities shall have ceased to be outstanding. In
addition, as to any Registrable Securities which are CVRs, such CVRs shall cease
to be Registrable Securities upon the earlier to occur of (A) the date such CVRs
cease to be Registrable Securities pursuant to the preceding sentence and (B)
the full and complete satisfaction by the Company of all of its obligations with
respect to such CVRs pursuant to the terms and conditions of the Contingent
Value Rights Agreement.

         "Registration Expenses" means (i) all registration, filing and NASD
fees, (ii) fees and expenses of complying with securities or blue sky laws
(including reasonable fees and disbursements of counsel in connection with blue
sky qualifications of the shares covered by such registration), (iii) printing
expenses, (iv) internal expenses of the Company (including all salaries and
expenses of its officers and employees performing legal and accounting duties),
(v) reasonable fees and disbursements of counsel for the Company and of its
independent certified public accountants, including the expenses relating to
"cold comfort" letters requested pursuant thereto, (vi) not more than $25,000 of
reasonable fees and disbursements of one counsel for the Stockholders in
connection with their participation in any offering, (vii) the reasonable fees
and

                                       3
<PAGE>

expenses of special experts retained by the Company in connection with such
registration, premiums and other costs of policies of insurance against
liabilities arising out of the public offering of the Registrable Securities
being registered (if the Company elects to obtain any such insurance), and
(viii) any fees and disbursements of underwriters customarily paid by issuers or
sellers of securities, but excluding underwriting discounts and commissions and
transfer taxes, if any, and the fees and expenses of counsel for the
underwriters.

         "Requesting Holder" means, in respect of any registration pursuant to
Section 2 hereof, any holder of Registrable Securities who gives notice to the
Company of its request to include Registrable Securities in such registration.

         "Rule 144" means Rule 144 promulgated by the Commission under the
Securities Act as such rule may be amended from time to time, or any similar
rule then in force.

         "Securities Act" means the Securities Act of 1933, or any similar
United States statute, and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time.

         "Stockholders" means any of the DLJ Entities, Byrne or Marsh, acting on
behalf of itself, other related Marsh & McLennan Capital, Inc. entities and/or
Marsh & McLennan Risk Capital Holdings, Ltd. and/or Risk Capital Reinsurance
Company.

         Section 2.  Registration under Securities Act

          (a)   Registration on Request

                  (i) Request. If at any time any DLJ Entity or Marsh requests
         in writing (the requesting Person being referred to as the "Initiating
         Stockholder") that the Company effect the registration under the
         Securities Act of a specified number of the Registrable Securities held
         by it and specifying the intended method of disposition thereof, a copy
         of which request (the "Company Notice") shall be sent by the Company to
         the other Persons entitled to request registration under this Section
         2(a) that have not made such registration request (the "Other
         Stockholders"), the Company will, in accordance with the provisions of
         Section 2(c) hereof, use its commercially reasonable efforts to effect
         the registration under the Securities Act of the Registrable Securities
         which the Company has been so requested to register by the Initiating
         Stockholder and any Registrable Securities of the same class and type
         which the Company has been so requested to register by any Other
         Stockholders, so long as such

                                       4
<PAGE>

         Other Stockholders have requested that such Registrable Securities be
         included in such registration within 10 days of the date of the Company
         Notice, for disposition in accordance with the intended method or
         methods of disposition stated in the request by the Initiating
         Stockholder, all to the extent requisite to permit the disposition (in
         accordance with the intended methods thereof as aforesaid) of
         Registrable Securities to be so registered; provided that the Company
         shall not be required to effect (A) more than three registrations
         requested by the DLJ Entities pursuant to this Section 2(a), (B) more
         than two registrations requested by Marsh pursuant to this Section
         2(a), (C) any registration under this Section 2(a) unless the
         Registrable Securities requested to be included therein by the
         Initiating Stockholder, in the reasonable judgment of the Board
         exercised in good faith, have an aggregate fair market value of at
         least $25,000,000, or unless the Registrable Securities requested to be
         included therein constitute all of the Registrable Securities of the
         class and type of Registrable Securities requested to be so registered
         that are then owned by the Initiating Stockholder (and, in case of any
         DLJ Entity, all other DLJ Entities), it being understood that if the
         Registrable Securities requested to be registered by any Initiating
         Stockholder (i) have an aggregate fair market value of less than
         $25,000,000 and (ii) include both Common Shares and CVRs, the
         requirements of this paragraph (C) shall be deemed to be satisfied if
         the Registrable Securities of at least one of the class and type of
         Registrable Securities requested to be included therein by such
         Initiating Stockholder constitute all of the Registrable Securities of
         that class and type of Registrable Securities then owned by the
         Initiating Stockholder (and, in the case of any DLJ Entity, all other
         DLJ Entities) or (D) any registration under this Section 2(a) prior to
         the earlier of the date that is six months after the effective date of
         the Company's most recent registration statement (other than a
         registration on Form S-4 or Form S-8 or any successor or similar forms)
         pursuant to which Registrable Securities are to be or were sold
         pursuant to this Section 2(a) or the date that is three months after
         the effective date of the Company's most recent registration statement
         (other than a registration on Form S-4 or Form S-8 or any successor or
         similar forms) pursuant to which the DLJ Entities or Marsh were
         entitled to request that Registrable Securities be sold pursuant to
         Section 2(b). Any request by an Initiating Stockholder pursuant to the
         first sentence of this Section 2(a) shall indicate that such Initiating
         Stockholder intends, in good faith, to dispose of all of the
         Registrable Securities as to which a request is made pursuant to this
         Section 2(a) pursuant to an underwritten public offering; provided that
         such intention shall not preclude a change to the plan of distribution
         to allow block trades, it being understood that no such change may be
         made with the intention of converting such registration into the
         functional equivalent of an "equity shelf." A request to register
         Registrable Securities pursuant to this Section 2(a) that is made by
         any DLJ Entity or Marsh, as the case may be, in its capacity as an
         "Other Stockholder" shall not reduce the number

                                       5
<PAGE>

         of registrations available to such entity pursuant to paragraph (A) or
         (B), as the case may be, of this Section 2(a)(i).

                 (ii)  Effective Registration Statement. A registration
         requested pursuant to this Section 2(a) shall not be deemed to be
         effected pursuant to Section 2(a) (A) if a registration statement with
         respect thereto shall not have become effective and remained effective
         for a period of at least 180 days (or such shorter period in which the
         Registrable Securities included in such registration pursuant to
         Section 2(a) have been sold thereunder), (B) if, after it has become
         effective, such registration is interfered with for any reason by any
         stop order, injunction or other order or requirement of the Commission
         or any other governmental agency or any court, and the result of such
         interference is to prevent the holders of Registrable Securities to be
         sold thereunder from disposing of at least 75% of the Registrable
         Securities included in such registration pursuant to Section 2(a) in
         accordance with the intended methods of disposition or (C) if the
         conditions to closing specified in the purchase agreement or
         underwriting agreement entered into in connection with any underwritten
         registration shall not be satisfied or waived with the consent of the
         holders of Registrable Securities that were to have been sold
         thereunder, other than as a result of any breach by any holder of its
         obligations thereunder or hereunder.

                 (iii) Expenses. The Company shall pay all Registration Expenses
         in connection with any registration requested pursuant to this Section
         2(a).

                 (iv)  Priority in Requested Registrations. If a requested
         registration pursuant to this Section 2(a) involves an underwritten
         offering, and the managing underwriter shall advise the Company in
         writing that, in its view, (i) the number of securities requested,
         pursuant to this Section 2(a), to be included in such registration
         (including Common Shares and CVRs which the Company proposes to
         include, whether or not for the sale for its own account, which are not
         Registrable Securities) or (ii) the inclusion of some or all of the
         Common Shares and CVRs owned by other shareholders of the Company
         (including Registrable Securities proposed to be included by any
         Stockholder pursuant to Section 2(b)), in either case, exceeds the
         number which can be sold in such offering without having an adverse
         impact on such offering, including the price at which such securities
         can be sold (the "Maximum Offering Size"), the Company will include in
         such registration, in the priority listed below, up to the Maximum
         Offering Size (A) first, Registrable Securities requested, pursuant to
         this Section 2(a), to be included in such registration by the DLJ
         Entities and Marsh, as the case may be, (pro rata as between them based
         on the number of Registrable Securities proposed to be so registered)
         and (B) second, Common Shares and/or CVRs requested to be included in
         such registration by the Company for its own account, by

                                       6
<PAGE>

         Byrne pursuant to Section 2(b) or by any other holder of Common Shares
         and/or CVRs having registration rights, in the case of this paragraph
         (B), pro rata among such holders on the basis of the number of Common
         Shares and/or CVRs requested to be so registered; provided that if, as
         a result of any reduction in Common Shares and/or CVRs to be sold as
         contemplated by this Section 2(a)(iv), the Initiating Stockholder is
         entitled to sell pursuant to such registration less than 65% of the
         Registrable Securities requested to be included pursuant to Section
         2(a), the request by the Initiating Stockholder that initiated such
         registration shall not reduce the number of registrations available to
         the Initiating Stockholder pursuant to paragraph (A) or (B), as the
         case may be, of Section 2(a)(i).

         (b)   Incidental Registration.

                  (i) Right to Include Registrable Securities. If the Company at
         any time proposes to register any Common Shares or CVRs under the
         Securities Act, whether for its own account or the account of a third
         party (other than by a registration (A) on Form S-4 or S-8 or any
         successor or similar forms, (B) relating to Common Shares issuable upon
         exercise of employee stock options or in connection with any employee
         benefit plan or (C) in connection with any direct or indirect exchange
         offer, amalgamation, merger, acquisition or similar transaction whether
         or not for sale for its own account), the Company will at each such
         time give prompt written notice to the Stockholders of its intention to
         do so and of such holders' rights under this Section 2(b). Upon the
         written request of any holder of Registrable Securities of the same
         class and type of securities which the Company proposes to register,
         made within 10 days after the receipt of any such notice (which request
         shall specify the Registrable Securities intended to be disposed of by
         such holder and the intended method of disposition thereof), the
         Company will, subject to the provisions of paragraph (iii) of this
         Section 2(b), use its reasonable efforts to effect the registration
         under the Securities Act of all Registrable Securities which the
         Company has been so requested to register by the holders thereof, to
         the extent requisite to permit the disposition (in accordance with the
         intended methods thereof as aforesaid) of the Registrable Securities so
         to be registered; provided that (i) if such registration involves an
         underwritten offering, all such holders of Registrable Securities
         requesting to be included in such registration must enter into the
         underwriting agreement as contemplated by Section 2(d) hereof and (ii)
         if, at any time after giving written notice of its intention to
         register any securities pursuant to this Section 2(b) and prior to the
         effective date of the registration statement filed in connection with
         such registration, the Company shall determine for any reason not to
         register or to delay registration of such securities, the Company may,
         at its election, give written notice of such determination to all such
         shareholders and, thereupon, (A) in the case of a determination not to
         register, shall be

                                       7
<PAGE>

         relieved of its obligation to register any Registrable Securities in
         connection with such registration and (B) in the case of a
         determination to delay registering, shall be permitted to delay
         registering any Registrable Securities, for the same period as the
         delay in registering such other securities.

                 (ii)  Expenses. The Company shall pay all Registration Expenses
         in connection with any registration requested pursuant to this Section
         2(b).

                 (iii) Priority in Incidental Registrations. If a registration
         pursuant to this Section 2(b) involves an underwritten offering (other
         than in the case of a registration under Section 2(a)), and the
         managing underwriter shall advise the Company in writing, that, in its
         opinion, the number of securities requested and otherwise proposed to
         be included in such registration exceeds the Maximum Offering Size, the
         Company will include in such registration, in the following priority,
         up to the Maximum Offering Size, (1) first, the securities proposed to
         be issued by the Company, (2) second, all Registrable Securities
         proposed to be registered for the account of the Stockholders and
         requested to be included in such registration, pro rata in accordance
         with the number of Registrable Securities proposed to be registered by
         such Stockholders and (3) third, all Common Shares and CVRs proposed to
         be registered for the account of other Persons, if any, having
         registration rights granted after the date hereof and requested to be
         included in such registration (whether or not such request arises from
         a demand registration right granted to such person), pro rata in
         accordance with the number of Common Shares and CVRs proposed to be
         registered by such other Persons, or otherwise allocated among such
         Persons in such proportion as such Persons and the Company shall agree.
         Notwithstanding the foregoing, after the 18 month anniversary of the
         Closing Date, the Persons referred to in clauses (2) and (3) shall
         include Common Shares and CVRs in any registration pursuant to this
         Section 2(b) pro rata in accordance with the number of Common Shares
         and CVRs requested to be included in such registration by all such
         Persons; provided that if, after such 18 month anniversary, a request
         pursuant to this Section 2(b) occurs in respect of an underwritten
         offering made at the request of any other Person pursuant to
         registration rights granted to such Person after the date hereof in
         connection with the issuance by the Company of securities, and the
         managing underwriter has advised the Company in writing, that, in its
         opinion, the number of securities requested and otherwise proposed to
         be included in such registration exceeds the Maximum Offering Size, the
         Company will include in such registration, in the following priority,
         up to the Maximum Offering Size, (1) first, the securities proposed to
         be registered by such Person and (2) second, all Common Shares and CVRs
         proposed to be registered for the account of other Persons (including
         the Stockholders), if any, requested to be included in such
         registration pro rata in accordance

                                       8
<PAGE>

         with the numbers of other securities proposed to be registered by the
         other Persons or otherwise allocated among such other Persons in such
         proportion as such holders and the Company shall agree.

          (c) Registration Procedures. If and whenever the Company is required
to use its reasonable efforts to effect the registration of any Registrable
Securities under the Securities Act as provided in Section 2(a) or Section 2(b)
the Company will as expeditiously as practicable:

                 (i)   prepare and file with the Commission the requisite
         registration statement to effect such registration and thereafter use
         its commercially reasonable efforts to cause such registration
         statement to become effective; provided that the Company may postpone
         the filing or effectiveness of a registration for a reasonable period
         not to exceed 90 days from the date of the request, if the Board
         reasonably believes that such registration might reasonably be expected
         to have an adverse effect on any proposal or plan to engage in any
         acquisition of assets or capital stock or any amalgamation, merger,
         consolidation, tender offer or similar transaction; or would otherwise
         require disclosure of information which the Board in its reasonable
         judgement determines should not be disclosed; provided further that no
         more than one postponement under this clause (i) or termination under
         clause (ii) below may be imposed in any twelve-month period.

                 (ii)  prepare and file with the Commission such amendments and
         supplements to such registration statement and the prospectus used in
         connection therewith as may be necessary to keep such registration
         statement continuously effective for a period of either (A) 180 days
         (without including in such period the number of days in any Delay
         Period (as hereinafter defined)) or (B) such shorter period as will
         terminate when all of the securities covered by such registration
         statement have been disposed of in accordance with the intended methods
         of disposition by the seller or sellers thereof set forth in such
         registration statement (but in any event not before the expiration of
         any longer period required under the Securities Act), and to comply
         with the provisions of the Securities Act with respect to the
         disposition of all securities covered by such registration statement;
         provided that the Company may terminate the effectiveness of a
         registration if the Board reasonably believes that such registration
         would reasonably be expected to have an adverse effect on any proposal
         or plan to engage in any acquisition of assets or capital stock or any
         amalgamation, merger, consolidation, tender offer or similar
         transaction or would otherwise require disclosure of information which
         the Board determines in its reasonable judgement should not be
         disclosed;

                 (iii) furnish to each Requesting Holder such number of
         conformed copies of such registration statement and of each such

                                       9
<PAGE>

         amendment and supplement thereto (in each case including all exhibits,
         but only one copy thereof to each such Requesting Holder), such number
         of copies of the prospectus contained in such registration statement
         (including each preliminary prospectus and any summary prospectus) and
         any other prospectus filed under Rule 424 under the Securities Act, in
         conformity with the requirements of the Securities Act, and such other
         documents in order to facilitate the disposition of the Registrable
         Securities owned by such Requesting Holder, as such Requesting Holder
         may reasonably request;

                 (iv) use its commercially reasonable efforts to register or
         qualify such Registrable Securities and other securities covered by
         such registration statement under such other securities or blue sky
         laws of such jurisdictions as each seller thereof shall reasonably
         request, to keep such registration or qualification in effect for so
         long as such registration statement remains in effect, and to take any
         other action which may be reasonably necessary or advisable to enable
         such seller to consummate the disposition in such jurisdictions of the
         securities owned by such seller; provided that the Company shall not
         for any such purpose be required to (A) qualify generally to do
         business as a foreign corporation in any jurisdiction where it would
         not otherwise be required to qualify but for the requirements of this
         clause (iv), (B) consent to general service of process in any such
         jurisdiction or (C) subject itself to taxation in such jurisdiction;

                 (v)  use its commercially reasonable efforts to cause all
         Registrable Securities covered by such registration statement to be
         registered with or approved by such other governmental agencies or
         authorities as may be necessary by virtue of the business and
         operations of the Company to enable the seller or sellers thereof to
         consummate the disposition of such Registrable Securities;

                 (vi) promptly notify each seller of Registrable Securities, at
         any time when a prospectus relating thereto is required to be delivered
         under the Securities Act, upon discovery that, or upon the discovery of
         the happening of any event as a result of which the prospectus included
         in such registration statement, as then in effect, includes an untrue
         statement of a material fact or omits to state any material fact
         required to be stated therein or necessary to make the statements
         therein not misleading in the light of the circumstances under which
         they were made, and at the request of any such seller promptly prepare
         and furnish to such seller a reasonable number of copies of a
         supplement to or an amendment of such prospectus as may be necessary so
         that, as thereafter delivered to the purchasers of such securities,
         such prospectus shall not include an untrue statement of a material
         fact or omit to state a material fact required to be stated therein or

                                       10
<PAGE>

         necessary to make the statements therein not misleading in the light of
         the circumstances under which they were made;

                 (vii)  otherwise use its commercially reasonable efforts to
         comply with all applicable rules and regulations of the Commission, and
         make available to its security holders, as soon as reasonably
         practicable, an earnings statement covering a period of at least twelve
         months, but not more than eighteen months, beginning with the first
         full calendar month after the effective date of such registration
         statement, which earnings statement shall satisfy the provisions of
         Section 11(a) of the Securities Act; and

                 (viii) use its commercially reasonable efforts to cause all
         such Registrable Securities covered by such registration statement to
         be listed on any national securities exchange (if such Registrable
         Securities are not already so listed), and on each other securities
         exchange, on which similar securities issued by the Company are then
         listed, if the listing of such Registrable Securities is then permitted
         under the rules of such exchange.

         The Company may require each seller of Registrable Securities as to
which any registration is being effected to furnish promptly to the Company such
information regarding such seller and such seller's Registrable Securities as
the Company may from time to time reasonably request and such other information
as may be legally required in connection with such registration.

         Each holder of Registrable Securities agrees that upon receipt of any
notice from the Company of the happening of any event of the kind described in
clause (vi) of this Section 2(c), such holder will forthwith discontinue such
holder"s disposition of Registrable Securities pursuant to the registration
statement relating to such Registrable Securities until such holder"s receipt of
the copies of the supplemented or amended prospectus contemplated by clause (vi)
of this Section 2(c) (a "Delay Period") and, if so directed by the Company, such
holder will deliver to the Company all copies, other than permanent file copies
then in such holder"s possession, of the prospectus relating to such Registrable
Securities current at the time of receipt of such notice.

         (d) Underwritten Offerings. The DLJ Entities will have the right, in
their sole discretion, to select an underwriter or underwriters in connection
with any underwritten offering resulting from the exercise by any DLJ Entity of
a demand for registration under Section 2(a), in which offering the Registrable
Securities to be registered by the DLJ Entities pursuant to Section 2(a)
constitute more than 50% of all Registrable Securities to be registered pursuant
to Section 2(a). Such underwriter or underwriters may include any Affiliate of
any DLJ Entity. The Board shall select, in its sole discretion, the underwriter
or underwriters in connection with any other underwritten offering; provided
that, in any underwritten offering in which Marsh is the Initiating Stockholder,
the lead

                                       11
<PAGE>

underwriters of such offering shall be reasonably acceptable to Marsh and;
provided further that, in any underwritten offering in which at least 30% of the
securities to be sold are owned by the DLJ Entities, the DLJ Entities shall have
the right to designate one co-lead underwriter in connection with such offering
(which will not, unless the Company consents, be the book-runner). Such
underwriter may include any Affiliate of any DLJ Entity. The underwriting
agreement shall be reasonably satisfactory in substance and form to the Board
and shall contain such representations and warranties by the Company and by the
selling stockholders and such other terms as are generally prevailing in
agreements of this type, including, without limitation, indemnities to the
effect and to the extent provided in Section 2(f). No Person may participate in
any underwritten registration hereunder unless such Person (i) agrees to sell
such Person's securities on the basis provided in any underwriting arrangements
reasonably approved by the Board that are consistent with the provisions of this
Agreement and (ii) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents reasonably
required under the terms of such underwriting arrangements and the provisions of
this Agreement.

         (e) Holdback Agreements. Each holder of Registrable Securities agrees
for the benefit of the Company, so long as the Company and its controlling
stockholders agree to be similarly bound, not to effect any sale or distribution
of any equity securities of the Company, or any securities convertible into or
exchangeable or exercisable for such securities, including a sale pursuant to
Rule 144 under the Securities Act (or any similar provision then in force),
during the 30 day period before the effective date of such registration
statement (except as part of such registration statement) or during the period
after such effective date that such managing underwriter or the Board, in their
reasonable judgement, shall agree (but not to exceed 180 days); provided that
the transferees in any sale not prohibited hereunder (other than as part of such
underwritten public offering) shall agree to be bound by the terms of this
Section 2(e).

         (f) Indemnification.

                 (i)  Indemnification by the Company. In the event of any
         registration of any securities of the Company under the Securities Act
         pursuant to this Section 2, the Company will, and hereby does,
         indemnify and hold harmless, the seller of any Registrable Securities
         covered by such registration statement, its directors, officers, agents
         and employees, each other Person who participates as an underwriter in
         the offering or sale of such securities and each other Person, if any,
         who controls such seller or any such underwriter within the meaning of
         the Securities Act, against any losses, claims, damages or liabilities,
         joint or several, to which such seller or any such director, officer,
         agent, employee, underwriter or controlling person may become subject
         under the Securities Act or otherwise, insofar as such losses, claims,
         damages or liabilities (or actions or proceedings,

                                       12
<PAGE>

         whether commenced or threatened, in respect thereof) arise out of or
         are based upon (A) any untrue statement or alleged untrue statement of
         any material fact contained (x) in any registration statement under
         which such securities were registered under the Securities Act, any
         preliminary prospectus, final prospectus or summary prospectus
         contained therein or used in connection with the offering of securities
         covered thereby, or any amendment or supplement thereto or any document
         included by reference therein, or (y) in any application or other
         document or communication (in this Section 2(f) collectively called an
         "application") executed by or on behalf of the Company or based upon
         written information furnished by or on behalf of the Company filed in
         any jurisdiction in order to qualify any securities covered by such
         registration statement under the "blue sky" or securities laws thereof,
         or (B) 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, and the Company will reimburse such seller and
         each such director, officer, agent, employee, underwriter and
         controlling person for any legal or any other expenses incurred by them
         in connection with investigating or defending any such loss, claim,
         liability, action or proceeding; provided that the Company shall not be
         liable in any such case to the extent that any such loss, claim,
         damage, liability (or action or proceeding in respect thereof) or
         expense arises out of or is based upon an untrue statement or alleged
         untrue statement, or omission or alleged omission, made in such
         registration statement, any such preliminary prospectus, final
         prospectus, summary prospectus, amendment or supplement, or in any
         application, in reliance upon and in conformity with written
         information prepared and furnished to the Company by such seller
         specifically for use in the preparation thereof which information
         contained any untrue statement of any material fact or omitted to state
         therein a material fact required to be stated therein or necessary to
         make the statements therein not misleading; and provided further that
         the Company shall not be liable to any Person who participates as an
         underwriter in any such registration or any other Person who controls
         such underwriter within the meaning of the Securities Act, in any such
         case to the extent that any such loss, claim, damage, liability (or
         action or proceeding in respect thereof) or expense arises out of such
         Person's failure to send or give a copy of the final prospectus, as the
         same may be then supplemented or amended (provided it has been made
         available to such Person in accordance with the terms hereof), to the
         Person asserting an untrue statement or alleged untrue statement or
         omission or alleged omission at or prior to the written confirmation of
         the sale of the securities to such Person if such statement or omission
         was corrected in such final prospectus. Such indemnity shall remain in
         full force and effect regardless of any investigation made by or on
         behalf of such seller or any such director, officer, agent, employee,
         underwriter or controlling Person and shall survive the transfer of
         such securities by such seller. The Company shall not be obligated to
         pay the fees and expenses of

                                       13
<PAGE>

         more than one counsel or firm of counsel for all parties indemnified in
         respect of a claim for each jurisdiction in which such counsel is
         required unless in the reasonable judgment of counsel for the
         indemnified party a conflict of interest may exist between such
         indemnified party and any other indemnified party in respect of such
         claim.

                (ii)  Indemnification by the Sellers. The Company may require,
         as a condition to including any Registrable Securities i n any
         registration statement filed pursuant to this Section 2, that the
         Company shall have received an undertaking satisfactory to it from the
         prospective seller of such Registrable Securities, to indemnify and
         hold harmless (in the same manner and to the same extent as set forth
         in Section 2(f)(i)) the Company, each director of the Company, each
         officer of the Company and each other Person, if any, who controls the
         Company within the meaning of the Securities Act, with respect to any
         statement or alleged statement in or omission or alleged omission from
         such registration statement, any preliminary prospectus, final
         prospectus or summary prospectus contained therein, or any amendment or
         supplement thereto, or any application, if such statement or alleged
         statement or omission or alleged omission was made in reliance upon and
         in conformity with written information prepared and furnished to the
         Company by such seller, as to such seller, specifically for use in the
         preparation of such registration statement, preliminary prospectus,
         final prospectus, summary prospectus, amendment or supplement, or such
         application, which information contained any untrue statement of any
         material fact or omitted to state therein a material fact required to
         be stated therein or necessary to make the statements therein not
         misleading. Such indemnity shall remain in full force and effect,
         regardless of any investigation made by or on behalf of the Company or
         any such director, officer or controlling Person and shall survive the
         transfer of such securities by such seller. The indemnity provided by
         each seller of securities under this Section 2(f)(ii) shall be provided
         severally, and not jointly or jointly and severally with any other
         seller or prospective seller of securities, and shall be limited in
         amount to the net amount of proceeds received by such seller from the
         sale of Registrable Securities pursuant to such registration statement.

                (iii) Notices of Claims, etc. Promptly after receipt by an
         indemnified party of notice of the commencement of any action or
         proceeding involving a claim referred to in the preceding subdivisions
         of this Section 2(f), such indemnified party will, if a claim in
         respect thereof is to be made against an indemnifying party, give
         written notice to the latter of the commencement of such action;
         provided that the failure of any indemnified party to give notice as
         provided herein shall not relieve the indemnifying party of its
         obligations under the preceding subdivisions of this Section 2(f),
         except to the extent that the indemnifying party is materially
         prejudiced by such failure to give notice. In case any such

                                       14
<PAGE>

         action is brought against an indemnified party, unless in such
         indemnified party's reasonable judgment a conflict of interest between
         such indemnified and indemnifying parties may exist in respect of such
         claim, the indemnifying party shall be entitled to participate in and
         to assume the defense thereof, jointly with any other indemnifying
         party similarly notified to the extent that it may wish, with counsel
         reasonably satisfactory to such indemnified party. No indemnifying
         party shall, without the consent of the indemnified party, consent to
         entry of any judgment or enter into any settlement which does not
         include as an unconditional term thereof the giving by the claimant or
         plaintiff to such indemnified party of a release from all liability in
         respect to such claim or litigation.

                 (iv) Other Indemnification. Indemnification similar to that
         specified in the preceding subdivisions of this Section 2(f) (with
         appropriate and reasonable modifications) shall be given by the Company
         and each seller of Registrable Securities with respect to any required
         registration or other qualification of securities under any federal,
         state or provincial law or regulation of any governmental authority,
         other than the Securities Act.

                  (v) Indemnification Payments. The indemnification required by
         this Section 2(f) shall be made by periodic payments of the amount
         thereof during the course of the investigation or defense, as and when
         bills are received or expense, loss, damage or liability is incurred,
         subject to refund if the party receiving such payments is subsequently
         found not to have been entitled thereto hereunder.

                 (vi) Contribution. In order to provide for just and equitable
         contribution in circumstances under which the indemnity contemplated by
         this Section 2(f) is for any reason not available, the parties required
         to indemnify by the terms hereof shall contribute to the aggregate
         losses, liabilities, claims, damages and expenses of the nature
         contemplated by such indemnity agreement incurred by the Company, any
         seller of Registrable Securities and one or more of the underwriters,
         except to the extent that contribution is not permitted under Section
         11(f) of the Securities Act. In determining the amounts which the
         respective parties shall contribute, there shall be considered the
         relative benefits received by each party from the offering of the
         Registrable Securities (taking into account the portion of the proceeds
         of the offering realized by each), the parties' relative knowledge and
         access to information concerning the matter with respect to which the
         claim was asserted, the opportunity to correct and prevent any
         statement or omission and any other equitable considerations
         appropriate under the circumstances. The Company and each Person
         selling securities agree with each other that no seller of Registrable
         Securities shall be required to contribute any amount in excess of the
         amount such seller would have been required to pay to an

                                       15
<PAGE>

         indemnified party if the indemnities under clauses (i) and (ii) above
         of this Section 2(f) were available. The Company and each such seller
         agree with each other and the underwriters of the Registrable
         Securities, if requested by such underwriters, that it would not be
         equitable if the amount of such contribution were determined by pro
         rata or per capita allocation (even if the underwriters were treated as
         one entity for such purpose) or for the underwriters" portion of such
         contribution to exceed the percentage that the underwriting discount
         bears to the initial public offering price of the Registrable
         Securities. For purposes of this clause (vi), each Person, if any, who
         controls an underwriter within the meaning of Section 15 of the
         Securities Act shall have the same rights to contribution as such
         underwriter, and each director and each officer of the Company who
         signed the registration statement, and each Person, if any, who
         controls the Company or a seller of Registrable Securities within the
         meaning of Section 15 of the Securities Act shall have the same rights
         to contribution as the Company or a seller of Registrable Securities,
         as the case may be.

       Section 3. Other Registration Rights. Notwithstanding anything to the
     contrary in this Agreement, the Company shall be permitted to grant to any
     Person the right to request that the Company to register any equity
     securities of the Company, any CVRs, or any securities convertible or
     exchangeable into or exercisable for such securities, without the consent
     of holders of any Registrable Securities, so long as no such registration
     rights conflict with or are senior to, or would result in a delay in
     exercise or consummation of, the rights granted pursuant to Section 2(a) or
     Section 2(b) hereunder (other than in the manner contemplated by the final
     sentence of Section 2(b)(iii)).

         Section 4.  Markel Guarantee. Markel hereby guarantees the performance
     by the Company of all of its obligations under this Agreement.

         Section 5. Amendments and Waivers. This Agreement may be amended and
     the Company may take any action herein prohibited, or omit to perform any
     act herein required to be performed by it, only if the Company shall have
     obtained the written consent to such amendment, action or omission to act
     of the holders of at least a majority of all Registrable Securities held by
     the DLJ Entities, on the one hand, and by Marsh, on the other hand.

         Section 6.  Notices. All communications provided for hereunder shall be
     in writing and shall be delivered personally or by facsimile or sent by
     first-class mail and addressed to Marsh and Byrne at the address that each,
     respectively, shall have furnished to the Company in writing, and

                                       16
<PAGE>

         if to the Company to:

Markel Holdings Inc.

c/o Markel Corporation

451 Cox Road

Glen Allen, Virginia 23059

Attention: Steven A. Markel

Facsimile: (804) 527-3810

         and with a copy to:

McGuire, Woods, Battle & Boothe LLP

One James Center

Richmond, Virginia 23219

Attention: Leslie A. Grandis

Facsimile: (804) 775-1061

         and if to any DLJ Entity to:

DLJ Merchant Banking

277 Park Avenue

New York, New York 10172

Attention: David L. Jaffe

         and with a copy to:

Davis Polk & Wardwell

450 Lexington Avenue

                                       17
<PAGE>

New York, New York 10017

Attention: George R. Bason, Jr.

Facsimile: (212) 450-4800

         Section 7. Binding Agreement. This Agreement shall be binding upon and
inure to the benefit of and be enforceable by the parties hereto and their
respective successors and assigns; provided that the rights accorded the DLJ
Entities herein shall not inure to the benefit of any transferee or subsequent
holder of any Registrable Securities, except to a Permitted Transferee acquiring
Registrable Securities who has executed and delivered to the Company an
agreement to be bound by this Agreement. Any such Permitted Transferee shall
thereafter have all the rights accorded to the DLJ Entities hereunder.
Notwithstanding the foregoing, (i) no Permitted Transferee obtaining its
Registrable Securities as a result of a distribution in kind to all or
substantially all of the limited partners of any DLJ Entity shall be entitled to
the benefits of this Agreement (ii) no DLJ Partner or DLJ Associate may be an
Initiating Stockholder, and (iii) all notices to any Permitted Transferee shall
be deemed to have been satisfactorily given for purposes of this Agreement if
given to DLJ Merchant Banking, Inc. at 277 Park Avenue, New York, New York
10172; Attention: David L. Jaffe; Facsimile No: 212-892-7552, which shall have
sole responsibility for giving notice to such Permitted Transferees and
coordinating the participation by such Permitted Transferees in any registration
of Registrable Securities pursuant hereto.

         Section 8.  Descriptive Headings. The descriptive headings
of the several sections and paragraphs of this Agreement are inserted for
reference only and shall not limit or otherwise affect the meaning hereof.

         Section 9.  Specific Performance. The parties hereto recognize and
agree that money damages may be insufficient to compensate the holders of any
Registrable Securities for breaches by the Company of the terms hereof and,
consequently, that the equitable remedy of specific performance of the terms
hereof will be available in the event of any such breach.

         Section 10. Effectiveness. This Agreement shall be effective as of the
Closing Date (as defined in the Merger Agreement) and the TNA Registration
Rights Agreement shall automatically terminate as of such date.

                                       18
<PAGE>

               Section 11. Termination. This Agreement shall automatically
          terminate on the earlier of: (i) the date that is five years from the
          Closing Date (as defined in the Merger Agreement) or (ii), if the
          Closing Date does not occur, the termination of the Merger Agreement.

               Section 12. Governing Law. All questions concerning the
          construction, validity and interpretation of this agreement will be
          construed and enforced in accordance with, and the rights of the
          parties shall be governed by, the internal laws, and not the law of
          conflicts, of the State of New York.

               Section 13. Counterparts. This Agreement may be executed
          simultaneously in any number of counterparts, each of which shall be
          deemed an original, but all such counterparts shall together
          constitute one and the same instrument.

               Section 14. Entire Agreement. This Agreement, together with the
          Merger Agreement, is intended by the parties hereto as a final
          expression of their agreement and intended to be a complete and
          exclusive statement of their agreement and understanding in respect to
          the subject matter contained herein. This Agreement supersedes all
          prior agreements and understandings between the parties with respect
          to such subject matter.

                                       19
<PAGE>

              IN WITNESS WHEREOF, the parties have caused this Agreement to be
     executed and delivered as of the date first above written.

                                        MARKEL CORPORATION

                                        By: /s/ Alan I. Kirshner
                                            _________________________________
                                            Name: Alan I. Kirshner
                                            Title: Chairman

                                        MARKEL HOLDINGS INC.

                                        By: /s/ Alan I. Kirshner
                                            _________________________________
                                            Name: Alan I. Kirshner
                                            Title: Chairman

                                       20
<PAGE>

                                        DLJ INTERNATIONAL PARTNERS, C.V.
                                        By: DLJ MERCHANT BANKING, INC.
                                            Advisory General Partner

                                        By: /s/ David Jaffe
                                            _________________________________
                                            Name: David Jaffe
                                            Title: Managing Director

                                        DLJ OFFSHORE PARTNERS, C.V.
                                        By: DLJ MERCHANT BANKING, INC.
                                            Advisory General Partner

                                        By: /s/ David Jaffe
                                            _________________________________
                                            Name: David Jaffe
                                            Title: Managing Director

                                        DLJMB OVERSEAS PARTNERS, C.V.
                                        By: DLJ MERCHANT BANKING, INC.
                                            Advisory General Partner

                                        By: /s/ David Jaffe
                                            _________________________________
                                            Name: David Jaffe
                                            Title: Managing Director

                                       21
<PAGE>

                                        DLJ MERCHANT BANKING
                                         FUNDING, INC.

                                                 /s/ Ivy Dodes
                                        By: ---------------------------------
                                            Name:    Ivy Dodes
                                            Title:   Vice President

                                        DLJ FIRST ESC, L.P.
                                        By: DLJ LBO PLANS MANAGEMENT
                                            CORPORATION, its General Partner

                                                 /s/ Ivy Dodes
                                        By: ---------------------------------
                                            Name:    Ivy Dodes
                                            Title:   Vice President

                                        DONALDSON, LUFKIN & JENRETTE
                                         SECURITIES CORPORATION

                                                 /s/ Ivy Dodes
                                        By: ---------------------------------
                                            Name:    Ivy Dodes
                                            Title:   Vice President

                                       22
<PAGE>

                                        MARSH & MCLENNAN CAPITAL, INC. on
                                        behalf of itself, MARSH & MCLENNAN RISK
                                        CAPITAL HOLDINGS, LTD., other related
                                        MARSH & MCLENNAN CAPITAL, INC.
                                        entities and RISK CAPITAL REINSURANCE
                                        COMPANY

                                        By: /s/ Richard A. Goldman
                                            _________________________________
                                            Name: Richard A. Goldman
                                            Title: Finance Director

                                       23
<PAGE>

                                        JOHN J. BYRNE, on his own behalf and on
                                        behalf of certain entities as to which,
                                        with respect to Common Shares held by
                                        such entities, he has voting and
                                        dispositive power
                                                 /s/ John J. Byrne
                                         --------------------------------------

                                       24

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