Exhibit 99.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

I, W. Marston Becker, Acting Chief Executive Officer of Trenwick Group Ltd.,
hereby certify to the best of my knowledge and belief that this Quarterly Report
on Form 10-Q fully complies with the requirements of Section 13(a) or 15(d) of
the Securities and Exchange Act of 1934 (15 U.S.C. 78m(a) or 78o(d)) and that
the information contained in this Quarterly Report on Form 10-Q fairly
represents, in all material respects, the financial condition and results of
operations of Trenwick Group Ltd.

Date:  May 14, 2003


/s/ W. Marston Becker
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W. Marston Becker
Acting Chief Executive Officer