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                                                                    EXHIBIT 10.4

                               MARKEL CORPORATION

                              RESTRICTED STOCK UNIT
                                 AWARD AGREEMENT

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     AWARDED TO             VESTING SCHEDULE                 AWARD DATE
                          VESTING     PERCENTAGE
  Thomas S. Gayner          DATE       OF UNITS                1/1/03
                            ----       --------
                         12/31/08        100%
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     MARKEL CORPORATION (the "Company") grants you (the "Participant") the
opportunity to receive restricted stock units ("Units"). The number of Units
will be based on performance conditions as specified below. Until the Vesting
Date except as specifically provided below, the Units are forfeitable and
nontransferable. The Compensation Committee of the Company's Board of Directors
(the "Committee") will administer this Agreement and any decision of the
Committee will be final and conclusive. Capitalized terms not defined here have
the meanings provided in the Markel Corporation Omnibus Incentive Plan (the
"Plan").

     The terms of the award are:

     1.   Performance Conditions: The performance conditions are set forth on
          Exhibit A. Upon certification by the Committee of the completion of
          the performance condition, the dollar equivalent of the percentage of
          salary will be determined. The Participant will receive a number of
          Units determined by dividing the dollar equivalent by the Fair Market
          Value of a share of Company common stock. The Fair Market Value will
          be determined by using the closing price of Company common stock on
          the date that the completion of the performance condition is certified
          by the Committee or its designee (the "Determination Date").

     2.   Vesting For Units. The Units will become vested and nonforfeitable on
          the Vesting Date, provided the Participant is employed on that date or
          previously had an approved termination of employment as provided in
          Section 4. As soon as practicable after the Units become vested, the
          Company will issue to the Participant for each vested Unit a share of
          common stock of the Company.

     3.   Forfeiture of Units. If the Participant ceases to be an employee
          before the Vesting Date in circumstances other than as described in
          (a)-(d) below, any unvested Units will be forfeited. If the
          Participant ceases to be an employee before the Vesting Date in the
          circumstances set forth in (a) below, the

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          unvested Units will become fully vested and non-forfeitable, and
          shares will be issued promptly following the Participant's Retirement
          or death or Disability, as the case may be. If the Participant ceases
          to be an employee before the Vesting Date in the circumstances set
          forth in (b), (c) or (d) below, the number of Units set forth in this
          Award will be vested on a pro rata basis based on a fraction of the
          number of full months from the first anniversary of the Award Date
          until the date of termination divided by 60, and shares will be issued
          on the otherwise applicable Vesting Date. If the Participant ceases to
          be an employee before the Vesting Date in the circumstance set forth
          in (d) below, the Committee shall determine the number of Units set
          forth in this Award to be vested and the date that the vested Units
          will be issued.

               (a)  The Participant ceases to be an employee due to Retirement,
                    dies or incurs a Disability (as defined in the Plan);

               (b)  The Participant ceases to be an employee due to Early
                    Retirement (as defined in the Plan)

               (c)  The Participant's employment is terminated or interrupted
                    due to military service;

               (d)  The Committee determines that forfeiture should not occur
                    because the Participant had an approved termination of
                    employment. The Committee will in its sole discretion
                    determine whether or not to apply this provision and if so,
                    any additional terms or conditions applicable to the
                    determination, including but not limited to, whether or not
                    the vesting schedule should be adjusted.

     4.   Change of Control. Any unvested Units will become fully vested and
          non-forfeitable and will be paid to the Participant if, within 12
          months after a Change in Control, the Participant is involuntarily
          terminated without Cause or terminates employment for Good Reason.

     5.   Forfeiture and Restitution. If during the period of the Participant's
          employment and two years thereafter, the Participant (1) becomes
          associated with, recruits or solicits customers or other employees of
          the Employer for, is employed by, renders services to, or owns any
          interest in (other than any nonsubstantial interest, as determined by
          the Committee) any business that is in competition with Markel or its
          Subsidiaries, (2) has his employment terminated by his Employer for
          Cause, or (3) engages in, or has engaged in, conduct which the
          Committee determines to be detrimental to the interests of Markel, the
          Committee may, in its sole discretion, (A) cancel this Award, and/or
          (B) require the Participant to repay by delivery of an equivalent
          number of shares any payment received under this Award within the
          previous two years.

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     6.   Transfer Restrictions. The Participant's rights to the Units are not
          subject to sale, assignment, transfer, pledge, hypothecation or
          encumbrance.

     7.   Tax Withholding. Unless alternative arrangements are made by the
          Participant, the Company will withhold from the payment for the vested
          Units shares with a fair market value equal to any required foreign,
          federal, state, or local income, employment or other taxes imposed on
          the payment. The fair market value will be the closing sale price of
          the Company's common stock on the New York Stock Exchange on the
          Vesting Date.

     8.   Binding Effect. Subject to the limitations stated above, this
          Agreement will be binding upon and inure to the benefit of the
          Participant's legatees, distributee, and personal representatives and
          the successors of the Company.

     9.   Change in Capital Structure. The Units will be adjusted as the
          Committee determines is equitably required in the event of a dividend
          in the form of stock, spin-off, stock split-up, subdivision or
          consolidation of shares of Company Stock or other similar changes in
          capitalization.

     10.  Interpretation. This Agreement will be construed under and be governed
          by the laws of the Commonwealth of Virginia. THE UNITED STATES
          DISTRICT COURT FOR THE EASTERN DISTRICT OF VIRGINIA OR THE CIRCUIT
          COURT FOR THE COUNTY OF HENRICO SHALL HAVE EXCLUSIVE JURISDICTION OVER
          ANY DISPUTES ARISING OUT OF OR RELATED TO THE PLAN OR THIS AGREEMENT.

IN WITNESS WHEREOF, the Company has caused this Agreement to be signed, as of
the award date shown above.

                                          MARKEL CORPORATION


                                          By:      /s/  Alan I. Kirshner
                                             -----------------------------------
                                                         CHAIRMAN

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                                                                       EXHIBIT A

                             PERFORMANCE CONDITIONS
                                 1/1/03-12/31/03

The Restricted Stock Units, expressed in dollars as a percentage of base salary,
will be based on growth in book value per share of Markel Common Stock. For 2003
the relevant measure will be growth in book value per share for 2003.

Growth in Book Value Per Share    Value of Restricted Stock Units
                                  As % of Base Salary
Under 11%                         0%
11%                               18.75%
12%                               22.5%
13%                               30%
14%                               37.5%
15%                               45%
16%                               56.25%
17%                               67.5%
18%                               75%
19%                               82.5%
20%                               93.75%
21%                               108.75%
22%                               127.5%
23%                               150%
24%                               187.5%

For purposes of this arrangement, book value calculations are adjusted to
exclude the benefit of issuing equity securities at prices above the preceding
year end book value per share.

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