SHAREHOLDERS AGREEMENT

         SHAREHOLDERS  AGREEMENT  (this  "Agreement")  dated as of December  19,
1999, by and among Trenwick Group Inc., a Delaware corporation ("Trenwick"), and
the other parties  signatory  hereto (each, a  "Shareholder"  and together,  the
"Shareholders").

                                    RECITALS

         WHEREAS,   simultaneously   herewith   Trenwick  is  entering  into  an
Agreement,  Scheme of  Arrangement,  Plan of Merger and Plan of  Reorganization,
dated as of December  19,  1999,  by and among  LaSalle Re  Holdings,  a company
organized under the laws of Bermuda ("LaSalle Holdings"),  LaSalle Re Limited, a
company  organized  under the laws of Bermuda  ("LaSalle Re"),  Trenwick,  Gowin
Holdings  International  Limited,  a company organized under the laws of Bermuda
("New Holdings") and Trenwick Group (Delaware) Inc., a Delaware corporation (the
"Business Combination Agreement");

         WHEREAS, the Business Combination  Agreement provides that Trenwick and
LaSalle  Holdings  will be entering  into a series of  transactions  pursuant to
which (i) New Holdings  will become the holding  company of such  companies  and
(ii)  shareholders  of  LaSalle  Holdings  and  LaSalle Re and  stockholders  of
Trenwick  will  become  shareholders  of New  Holdings  as  set  forth  in  such
agreement;

         WHEREAS,  each  Shareholder  owns that number of (i) LaSalle  Holdings'
common shares, par value $1.00 per share (the "Common Shares"), and (ii) LaSalle
Re's exchangeable  non-voting shares (the "Non-Voting Shares" and, together with
the Common  Shares,  the  "Shares",  which term shall  include  Shares which are
acquired or may be acquired  upon the exercise of any and all options to acquire
Common Shares and Non-Voting Shares  ("Options"),  whether such Options exist on
the date  hereof or  otherwise)  set forth  next to such  Shareholder's  name on
Exhibit A hereto; and

         WHEREAS,  as a condition to its  willingness to enter into the Business
Combination  Agreement,  Trenwick has required that each Shareholder  agree, and
each  Shareholder  has agreed,  among other things,  to execute and deliver this
Agreement  with respect to the Shares owned (whether by conversion or otherwise)
by such Shareholder, on the terms and conditions provided for herein.

         NOW,  THEREFORE,  in  consideration  of the  foregoing  and the  mutual
representations,  warranties,  covenants and agreements  herein  contained,  the
parties hereto agree as follows:

         1.  Voting  Agreement.  At any meeting of the  shareholders  of LaSalle
Holdings  or  LaSalle Re called to vote upon the  Scheme of  Arrangement  or the
Business  Combination  Agreement or at any  adjournment  thereof or in any other
circumstances  upon which a vote,  consent or other approval of  shareholders of
LaSalle Holdings or LaSalle Re with respect to any of the other matters referred
to below is  sought,  each  Shareholder  hereby  agrees  to vote (or cause to be
voted) the Shares held of record or beneficially  by such  Shareholder as of the
applicable record date (i) in favor of the Scheme of Arrangement,  the execution
and  delivery by LaSalle  Holdings  and LaSalle Re of the  Business  Combination
Agreement  and the approval of the terms  thereof and each of the other  actions
contemplated  by the Business  Combination  Agreement,  this  Agreement  and any
actions required in furtherance  hereof and thereof;  (ii) against any action or
agreement  that would,  to its  knowledge,  result in a breach of any  covenant,
representation  or  warranty or any other  obligation  or  agreement  of LaSalle
Holdings  or  LaSalle  Re  under  the  Business  Combination  Agreement  or this
Agreement;  and (iii) against the following  actions  (other than the Scheme and
the transactions  contemplated by the Business Combination  Agreement):  (1) any
extraordinary   corporate   transaction,   such  as  a  merger,   consolidation,
amalgamation or other business combination  involving LaSalle Holdings or any of
its subsidiaries (including,  without limitation, LaSalle Re); (2) a sale, lease


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or  transfer  of a material  amount of assets of LaSalle  Holdings or any of its
subsidiaries(including,  without  limitation,  LaSalle Re) or a  reorganization,
recapitalization,  dissolution or liquidation of LaSalle  Holdings or any of its
subsidiaries (including,  without limitation, LaSalle Re); (3) (a) any change in
the majority of the Board of  Directors  of LaSalle  Holdings or LaSalle Re; (b)
any material change in the present capitalization of LaSalle Holdings or LaSalle
Re or any material  amendment of LaSalle Holdings' or LaSalle Re's Memorandum of
Association and Bye-laws;  (c) any other material change in LaSalle Holdings' or
LaSalle Re's corporate  structure or business;  or (d) any other action which is
intended,  or could reasonably be expected,  to impede,  interfere with,  delay,
postpone, discourage or materially adversely affect the Scheme of Arrangement or
the  transactions  contemplated  by the Business  Combination  Agreement or this
Agreement or the contemplated  economic  benefits of any of the foregoing.  Each
Shareholder  hereby revokes any proxy  previously  granted by it with respect to
the Shares.  Each Shareholder hereby agrees,  while this Agreement is in effect,
and except as  contemplated  hereby,  not to take any action that would make any
representation  or  warranty  of such  Shareholder  contained  herein  untrue or
incorrect or have the effect of preventing or disabling  such  Shareholder  from
performing his or its obligations under this Agreement;  provided, however, that
nothing in this Agreement  shall be deemed to prohibit or restrict in any manner
any Shareholder from selling, transferring, or otherwise disposing of any Shares
or Options to any person.  The provisions of this Section 1 shall  terminate and
no longer bind the  Shareholders  at such time as the LaSalle  Holdings Board of
Directors  either (A) withdraws or modifies its approval and  recommendation  of
the Business Combination Agreement pursuant to clause (x) of the second sentence
of  Section  5.3(b)(ii)  thereof  or (B)  terminates  the  Business  Combination
Agreement  pursuant to clause (y) of the second  sentence of Section  5.3(b)(ii)
thereof.

         2.   Representations  and  Warranties  of  Trenwick.   Trenwick  hereby
represents and warrants to each  Shareholder  that the execution and delivery of
this Agreement and the consummation of the transactions contemplated hereby have
been duly and validly  authorized  by the Board of  Directors of Trenwick and no
other  corporate  proceedings on the part of Trenwick are necessary to authorize
this  Agreement or to consummate  the  transactions  contemplated  hereby.  This
Agreement  has been duly and validly  executed  and  delivered  by Trenwick  and
constitutes  a valid and binding  agreement  of  Trenwick,  enforceable  against
Trenwick in accordance with its terms,  except that such  enforceability (i) may
be limited by bankruptcy, insolvency, moratorium or other similar laws affecting
or relating to enforcement of creditors' rights generally and (ii) is subject to
general principles of equity.

         3. Representations and Warranties of the Shareholders. Each Shareholder
hereby  represents  and  warrants,  severally  and not  jointly,  to Trenwick as
follows:

                  (a) Ownership of Shares and Options.  Such Shareholder,  as of
         the date  hereof,  (i) is the owner of the number of Shares and Options
         set forth next to such  Shareholder's name on Exhibit A hereto and (ii)
         has the sole power to vote (or to give any consent that may be required
         in respect of such Shares and  Options)  and dispose of such Shares and
         Options.

                  (b) Power;  Binding Agreement.  Such Shareholder has the legal
         capacity,  power and  authority  to enter into and  perform  all of its
         obligations   under  this  Agreement.   The  execution,   delivery  and
         performance of this Agreement by such  Shareholder will not violate any
         other agreement to which such Shareholder is a party including, without
         limitation,  any voting  agreement,  shareholders  agreement  or voting
         trust.  This Agreement has been duly and validly  authorized,  executed
         and delivered by such  Shareholder  and constitutes a valid and binding
         agreement of such Shareholder,  enforceable against such Shareholder in
         accordance with its terms,  except that such  enforceability (i) may be
         limited by  bankruptcy,  insolvency,  moratorium  or other similar laws
         affecting or relating to enforcement of creditors' rights generally and
         (ii) is subject to general principles of equity.


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                  (c) No Conflicts.  (A) No filing by such Shareholder with, and
         no permit, authorization, consent or approval of, any state, federal or
         foreign public body or authority is necessary for the execution of this
         Agreement by such  Shareholder and the consummation by such Shareholder
         of the transactions  contemplated  hereby and (B) neither the execution
         and delivery of this Agreement by such Shareholder nor the consummation
         by  such  Shareholder  of  the  transactions  contemplated  hereby  nor
         compliance by such Shareholder with any of the provisions  hereof shall
         (1)  conflict  with or result in any  breach  of any  provision  of the
         certificate of incorporation,  by-laws, trust or charitable instruments
         (or similar  documents) of such Shareholder,  (2) result in a violation
         or breach of, or constitute (with or without notice or lapse of time or
         both) a default (or give rise to any third party right of  termination,
         cancellation,  material  modification or acceleration) under any of the
         terms, conditions or provisions of any note, bond, mortgage, indenture,
         license, contract, agreement or other instrument or obligation to which
         such  Shareholder  is a party or by which he or it or any of his or its
         properties  or assets  may be bound or (3)  violate  any  order,  writ,
         injunction,  decree,  statute,  rule or  regulation  applicable to such
         Shareholder  or any of his or its  properties or assets,  except in the
         case of (A) or (B) for violations, breaches or defaults which would not
         in the  aggregate  materially  adversely  affect  the  ability  of such
         Shareholder to perform its obligations hereunder.

         4.  Adjustments  to  Prevent  Dilution,  Etc.  In the  event of a stock
dividend or  distribution,  or any change in LaSalle  Holdings'  or LaSalle Re's
capital  shares by reason of any  share  dividend,  split-up,  reclassification,
recapitalization, combination or the exchange of shares, the term "Shares" shall
be deemed to refer to and include the Shares as well as all such stock dividends
and  distributions  and any  shares  into  which or for  which any or all of the
Shares may be changed or exchanged.

         5.       Miscellaneous.

                  (a)  Entire  Agreement.  This  Agreement  contains  the entire
understanding  of the parties with respect to the subject  matter hereof and may
not be amended except by a writing signed by the parties. Except as specifically
provided  herein,  this  Agreement  is not  assignable  by  any of the  parties,
provided that none of the  transactions  described in Sections 2.1(b) and 2.1(c)
of the Business  Combination  Agreement  shall be  considered  an  assignment by
Trenwick.  This Agreement shall be binding upon the respective successors of the
parties  and  upon   transferees  of  the  Shares  who  are  Affiliates  of  the
transferring Shareholder.

                  (b) Notices. All notices,  requests, claims, demands and other
communications  hereunder  shall be in writing  and shall be given (and shall be
deemed to have been duly received if so given) by hand delivery, telegram, telex
or telecopy,  or by mail (registered or certified mail, postage prepaid,  return
receipt requested) or by any courier service, such as Federal Express, providing
proof of  delivery.  All  communications  hereunder  shall be  delivered  to the
respective parties at the following addresses:

         If to a Shareholder,  to the address of such  Shareholder  indicated on
Exhibit A hereto.

         If to Trenwick:

                      Trenwick Group Inc.
                      One Canterbury Green
                      Stamford, Connecticut 06901
                      Attention: Steve Bensinger and
                                     John Del Col, Esq.
                      Facsimile No.: (203) 353-5544



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                      with a copy to:

                      Baker & McKenzie
                      805 Third Avenue
                      New York, New York 10022
                      Attention: James R. Cameron, Esq.
                      Facsimile No.: (212) 891-3835


         If to New Holdings:

                      Gowin Holdings International Limited
                      c/o Appleby Spurling & Kempe
                      Cedar House
                      41 Cedar Avenue
                      P.O. Box Hm 1179
                      Hamilton Bermuda HMEX
                      Attention: Warren Cabral
                      Facsimile No: (441) 292-8666


                      With a copy to:

                      Baker & McKenzie
                      805 Third Avenue
                      New York, New York 10022
                      Attention: James R. Cameron, Esq.
                      Facsimile No.: (212) 891-3835


or to such  other  address  as the  person  to whom  notice  is  given  may have
previously furnished to the others in writing in the manner set forth above.

         (c) Notification by Shareholder. Each Shareholder shall notify Trenwick
from time to time, upon request,  of the number of Shares  beneficially owned by
such Shareholder.

         (d) Governing Law. This Agreement  shall be governed in all respects by
the laws of the State of  Delaware  without  regard  to any laws or  regulations
relating  to  choice of laws  (whether  of the  State of  Delaware  or any other
jurisdiction)  that would cause the application of the laws of any  jurisdiction
other than the State of Delaware.

         (e) Cooperation. Subject to the terms and conditions of this Agreement,
each of the parties  hereby  agrees to use its best efforts to take, or cause to
be taken,  all  action  and to do, or cause to be done,  all  things  necessary,
proper or advisable under  applicable  laws, rules and regulations to consummate
and make effective the actions  contemplated by this  Agreement.  In case at any
time after the  execution  of this  Agreement,  further  action is  necessary or
desirable to carry out the purposes of this  Agreement,  the proper officers and
directors  of each of the parties  shall take all such  necessary  or  desirable
action.

         (f) Specific  Performance.  Each of the parties  hereto  recognizes and
acknowledges  that a breach by it of any  covenants or  agreements  contained in
this Agreement will cause the other party to sustain  damages for which it would
not have an adequate remedy at law for money damages, and therefore, each of the
parties  hereto agrees that in the event of any such breach the aggrieved  party
shall be entitled to the remedy of specific  performance  of such  covenants and
agreements and injunctive  and other  equitable  relief in addition to any other
remedy to which it may be entitled, at law or in equity.



                                       4




         (g)  Counterparts.  This  Agreement  may be  executed  in  one or  more
counterparts,  each of which shall be deemed to be an original, but all of which
shall constitute one and the same Agreement.

         (h)  Definitions.  Capitalized  terms used but not defined herein shall
have the meanings set forth in the Business Combination Agreement.

         (i)  Descriptive  Headings.  The  descriptive  headings used herein are
inserted for convenience of reference only and are not intended to be part of or
to affect the meaning or interpretation of this Agreement.

         (j) Severability.  Whenever possible,  each provision or portion of any
provision  of  this  Agreement  will be  interpreted  in  such  manner  as to be
effective and valid under  applicable law but if any provision or portion of any
provision of this Agreement is held to be invalid,  illegal or  unenforceable in
any  respect  under  any  applicable  law  or  rule  in any  jurisdiction,  such
invalidity,  illegality or unenforceability  will not affect any other provision
or portion of any provision in such  jurisdiction,  and this  Agreement  will be
reformed,  construed  and  enforced  in such  jurisdiction  as if such  invalid,
illegal or  unenforceable  provision or portion of any  provision had never been
contained herein.

         (k) Termination.  Unless earlier  terminated as provided  herein,  this
Agreement  shall  terminate,  without  further  liability or  obligation  of the
parties  hereto,  including  liability for damages,  upon the earlier of (i) the
180th  calendar  day  following  the  termination  of the  Business  Combination
Agreement in accordance  with its terms and (ii)  consummation  of the Scheme of
Arrangement.









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         IN WITNESS WHEREOF, this Agreement has been executed by or on behalf of
each of the parties hereto, all as of the date first above written.


                               TRENWICK GROUP INC.


                               By:/s/ James F. Billett, Jr.
                                  ----------------------------------
                               Name:  James F. Billett, Jr.
                               Title: Chairman, President and Chief
                                      Executive Officer


                               SHAREHOLDERS:

                               COMBINED INSURANCE COMPANY OF AMERICA

                               By: /s/ Michael A. Conway
                                   ---------------------------------
                               Name:  Michael A. Conway
                               Title: Senior Vice President


                               VIRGINIA SURETY COMPANY, INC.

                               By: /s/ Michael A. Conway
                                   ---------------------------------
                               Name:  Michael A. Conway
                               Title: Vice President


                               AON RISK CONSULTANTS (BERMUDA) LTD.

                               By: /s/ Michael A. Conway
                                   ---------------------------------
                               Name:  Michael A. Conway
                               Title: Authorized Agent


                               CONTINENTAL CASUALTY COMPANY

                               By:  /s/ Robert V. Deutsch
                                   ---------------------------------
                               Name:  Robert V. Deutsch
                               Title: Senior Vice President and Chief
                                      Financial Officer


                               CNA (BERMUDA) SERVICES LIMITED

                               By:  /s/ Robert V. Deutsch
                                   ---------------------------------
                               Name:  Robert V. Deutsch
                               Title: Authorized Agent



                                       6




                                    EXHIBIT A




                                                      NUMBER OF
                                    NUMBER OF         EXCHANGEABLE
                                    COMMON SHARES     NON-VOTING       OPTIONS
SHAREHOLDER NAME                    OF LASALLE        SHARES OF        AND/OR
AND ADDRESS                         HOLDINGS          LASALLE RE       WARRANTS
- --------------------
Combined Insurance Company
of America                             322,715        1,221,750              0

Virginia Surety Company, Inc.          322,715        1,221,750              0

Aon Risk Consultants (Bermuda) Ltd.    555,244                0              0

Continental Casualty Company         1,425,354        1,963,896              0

CNA (Bermuda) Services Limited               0          318,150              0