Exhibit 8.1

                                McGuireWoods LLP
                                One James Center
                              901 East Cary Street
                               Richmond, VA 23219

                                                            April 12, 2001


Markel Corporation
4521 Highwoods Parkway
Glen Allen, VA 23060-6148

Ladies and Gentlemen:

     Reference is made to the prospectus and consent solicitation statement (the
"Prospectus and Consent Solicitation Statement") included in the registration
statement on Form S-4 (the "Registration Statement") being filed by you with the
Securities and Exchange Commission (the "Commission") under the Securities Act
of 1933, as amended (the "Securities Act"), relating to

     (1)  a proposed public offering (the "Offering") by you of 7.2% Notes due
          August 15, 2007 and 7.0% Notes due May 15, 2008 (the "Markel Notes")
          in exchange for outstanding Markel International Limited notes having
          the same principal amount, interest rate, redemption terms and payment
          and maturity dates (the "Terra Nova Notes") and

     (2)  a proposed solicitation by Markel Corporation of consents from holders
          of Terra Nova Notes to amend the indentures under which such notes
          were given, in respect of which holders of Terra Nova Notes who
          receive Markel Notes pursuant to the Offering would receive cash
          payments.

At your request, this opinion of counsel is being furnished to you for filing as
Exhibit 8.1 to the Registration Statement.

     In providing this opinion, we have examined and are relying on the truth
and accuracy at all relevant times of the statements and representations
contained in (i) the Registration Statement, (ii) a certificate provided to us
by an officer of Markel Corporation, and (iii) other information provided to us
by Markel Corporation. In rendering this opinion, we have assumed that the
transactions contemplated by the Prospectus and Consent Solicitation Statement
will be consummated in the manner described therein. We have further assumed in
rendering this opinion that the representations made in the Officer's
Certificate, which are made "to the best of [the] knowledge and belief" of the
officer who signed such certificate, are and will be correct without such
qualification.

     Based on the foregoing, it is our opinion that the discussion (the "Tax
Discussion") in the Prospectus and Consent Solicitation Statement that is
contained under the caption "Material U.S. Federal Income Tax Consequences", in
so far as it concerns conclusions of law, is an accurate general description,
subject to the assumptions, qualifications and limitations set forth therein, of
the material federal income tax consequences relating to the Offering and
Consent Solicitation and of the ownership of the Markel Notes.

     Our opinion is not binding on the Internal Revenue Service or the courts
and merely represents our best judgment based upon existing authorities and the
assumptions, qualifications and limitations noted above. Thus, no assurance can
be given that the Internal Revenue Service will not take a position contrary to
one or more of the tax results described in the Tax Discussion, or that a court
would not uphold such a contrary opinion, potentially with adverse tax
consequences.

     Our opinion is limited to the tax matters specifically addressed herein and
speaks as of the date hereof. We undertake no obligation to update this opinion
in the event there is either a change in the legal authorities or facts upon
which this opinion is based, or an inaccuracy in any of the representations upon



which we have relied in rendering this opinion, even though such a change or
inaccuracy may affect the accuracy of the Tax Discussion.

     Pursuant to the provisions of Rule 436(a) of the Rules and Regulations of
the Commission under the Securities Act, we hereby consent to the reference to
our Firm under the caption "Legal Matters" in the Prospectus and Consent
Solicitation Statement and to the filing of this opinion with the Commission as
an exhibit to the Registration Statement. In giving such opinion, we do not
admit that we are within the category of persons whose consent is required under
Section 7 of the Securities Act or the Rules and Regulations of the Commission
thereunder.

                                                     Very truly yours,

                                                     /s/  McGuireWoods LLP