Exhibit 99.4

                             AMENDMENT NO. 1 TO THE
                          REGISTRATION RIGHTS AGREEMENT

      This Amendment No. 1 to the Registration Rights Agreement (this
"Amendment"), dated as of the 6th day of September, 2002, is entered into by and
between TRENWICK GROUP LTD., a Bermuda company (the "Company"), on the one hand,
and EUROPEAN REINSURANCE COMPANY OF ZURICH, a corporation organized under the
laws of Switzerland (the "Option Writer") on the other hand.

                                    RECITALS

      WHEREAS, the Company and Option Writer have entered into an Amended and
Restated Catastrophe Equity Securities Issuance Option Agreement, dated as of
January 1, 2001 (the "Option Agreement"), concerning, among other things, the
issuance and sale of preferred shares of the Company; and

      WHEREAS, in connection with the Option Agreement, the Company and Option
Writer entered into a Registration Rights Agreement, dated as of the 1st day of
January, 2001 (the "Registration Rights Agreement"), which set forth certain
rights and obligations with respect to shares to be issued upon conversion of
such preferred shares of the Company;

      WHEREAS, the Company and the Option Writer have agreed to enter into a
Second Amended and Restated Catastrophe Equity Securities Issuance Option
Agreement, dated as of the date hereof (the "Second Option Agreement") and, in
connection therewith, desire to amend certain provisions of the Registration
Rights Agreement;

      NOW, THEREFORE, for and in consideration of the mutual promises of the
parties hereto, and for other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties hereto agree to amend
the Registration Rights Agreement as follows:

      1. In first recital of the Registration Rights Agreement, the defined term
"(the "Option Agreement") is hereby deleted and replaced with "(such agreement,
as subsequently amended as of January 25, 2002 and amended and restated as of
September 6, 2002, the "Option Agreement")".

      2. In Section 1, the definition of "Minimum Registration Amount" is hereby
deleted in its entirety and replaced with the following:


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            "Minimum Registration Amount" shall mean an amount of Conversion
      Shares having an aggregate Value of at least $15,000,000; provided,
      however, that if all three of the following conditions are satisfied, then
      Minimum Registration Amount shall mean an amount of Conversion Shares
      having an aggregate Value of at least 75% of the aggregate Value of all
      Conversion Shares outstanding: (i) there shall be no remaining obligation
      to purchase Preferred Shares under the Option Agreement, (ii) the
      aggregate Value of all Conversion Shares outstanding shall be less than
      $15,000,000 as a result of either (A) the issuance of an aggregate of less
      than 150,000 Preferred Shares pursuant to the Option Agreement or (B) the
      redemption of Preferred Shares by the Company so as to reduce the number
      of Preferred Shares outstanding at any time to less than 150,000, and
      (iii) no registrations shall previously have been requested pursuant to
      Section 3(a) hereof (other than registrations which, pursuant to Sections
      3(a)(ii) or 3(a)(iv) hereof, are not counted toward the number of
      registrations that the Company is obligated to effect pursuant to Section
      3(a) hereof).

      3. In Section 3(a) of the Registration Rights Agreement, the fourth
paragraph of such section is hereby deleted in its entirety and replaced with
the following:

      Notwithstanding the foregoing, the aggregate period of time during which
      the Company will be relieved of the requirement to file a registration
      statement shall in no event exceed one hundred and eighty (180)
      consecutive days with respect to each request, it being understood that
      the Company shall only have the right to delay the filing of a
      registration statement with respect to each request on the basis of one of
      the foregoing clauses ((1), (2), (3) or (4)) and shall not have the right
      to cumulate periods of delay with respect to such request under more than
      one such clause.

      4. In Section 3(a) of the Registration Rights Agreement, clause (iii) is
hereby deleted in its entirety and replaced with the following:

                  (iii) Selection of Underwriters. If a requested registration
            pursuant to this Section 3(a) involves an underwritten offering,
            Requesting Holders holding a majority of the Conversion Shares
            requested to be registered shall have the right to select the
            investment banker and manager that will administer the offering;
            provided, however that if such Requesting Holders select an
            investment banker and manager other than a firm listed on Exhibit A
            hereto, the Company shall have the right to approve such investment
            banker and manager, which approval shall not be unreasonably
            withheld, provided further, that the Company shall have the right to
            appoint a co-manager in all cases subject to the approval of
            Requesting Holders holding a majority of the Conversion Shares
            requested to be registered, which approval shall not be unreasonably
            withheld.


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      IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date and year first written above.

The Company:

Trenwick Group Ltd.

       /s/ John V. Del Col                     /s/ Alan L. Hunte
       ---------------------------             ----------------------------
By:    John V. Del Col                  By:    Alan L. Hunte
Title: Secretary                        Title: Executive Vice President and
                                               Chief Financial Officer


European Reinsurance Company of Zurich

       /s/ J. Scott Bradley                    /s/ David R. Whiting
       ---------------------------             ----------------------------
By:    J. Scott Bradley                 By:    David R. Whiting
Title: Member of Senior Management      Title: Member of Senior Management


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