Exhibit 99.1

Trenwick Group Ltd.                  Continental Building      Tel  441.292.4985
                                     25 Church Street          Fax 441.292.4878
                                     Hamilton HM 12
                                     Bermuda

NYSE Symbol: TWK

Contact: Coleman D. Ross, Executive Vice President and Chief Financial Officer -
441.292.4985

                               Trenwick Group Ltd.
                    Announces Second Quarter Earnings Charges

Hamilton, Bermuda, July 24, 2001 . . .

Trenwick  Group Ltd.  announced  today  that  operating  results  for the second
quarter of 2001 will be  adversely  affected by unusual  loss  activity and loss
reserve strengthening.

Second quarter 2001 after-tax operating results will include unusual loss
activity of $10.5 million, or $.28 per share, related to an accumulation of
catastrophic losses including Tropical Storm Allison and storms affecting the
Midwest United States. Insured property catastrophe losses in the United States
totaled approximately $4.5 billion in the second quarter - the second worst
quarter ended June 30th in the last ten years.

Trenwick strengthened its after-tax loss reserves in the second quarter by $51.6
million, or $1.39 per share. The reserve strengthening emanates from reported
loss activity and related increases in incurred but not reported reserves for
prior accident years in certain discontinued and non-renewed classes of business
as well as a reassessment of reserve levels in certain continuing classes of
business.

As previously announced, Trenwick's net income for the second quarter will also
be affected by a $2.2 million after-tax restructuring charge in conjunction with
the management changes effected at its London operations in April.

Full commentary on the financial results of the quarter, an updated forecast for
2001, and a discussion of the continuing improvement in pricing conditions will
be presented in Trenwick's second quarter earnings release scheduled for August
8, 2001 and a subsequent conference call on August 9, 2001.

Background Information
Trenwick is a Bermuda-based specialty insurance and reinsurance underwriting
organization with five distribution platforms operating through its subsidiaries
located in the United States, the United Kingdom and Bermuda. Trenwick America
Re provides treaty reinsurance to insurers of property and casualty risks in the
United States. Trenwick International underwrites specialty insurance as well as
treaty and facultative reinsurance on a worldwide basis. Chartwell Managing
Agents Limited is Trenwick's managing agency at Lloyd's. Canterbury Financial
Group underwrites U.S. property and casualty insurance through specialty program
administrators. LaSalle Re is a property and casualty reinsurer writing
worldwide specialist products with an emphasis on catastrophe coverage.

Each of Trenwick's  principal insurance and reinsurance  subsidiaries is rated A
(Excellent)  by A. M. Best  Company and has been  assigned a financial  strength
rating of A+ by Standard & Poor's.

Safe Harbor for Forward-Looking Statements
Certain statements made in this press release that are not based on current or
historical fact are forward-looking in nature including, without limitation,
statements containing words "believes," "anticipates," "plans," "projects,"
"intends," "expects," "estimates," "predicts," and words of similar import. Such
forward-looking statements, including in particular Trenwick's forecast of
future earnings, involve known and unknown risks, assumptions, uncertainties,
and other factors that may cause actual results, performance, or achievements of
Trenwick or its industry to differ materially from any future results,
performance, or achievements expressed or implied by such forward-looking
statements.

Trenwick has identified certain risk factors which could cause actual plans or
results to differ substantially from those included in any forward-looking
statements. These risk factors are discussed in Trenwick's Securities and
Exchange Commission filings, including but not limited to its most recent Form
10-K, Form 10-Q and Form 8-K filed with the Securities and Exchange Commission,
and such discussions regarding risk factors are hereby incorporated by reference
into this press release. Copies of such Securities and Exchange Commission
filings are available from Trenwick or directly from the Securities and Exchange
Commission.