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                                                                    EXHIBIT 10.7

[LETTERHEAD OF PLATINUN(TM)]

June 30, 2003

The St. Paul Companies, Inc.
385 Washington Street
St. Paul, MN 55102

Attention: Mr. Mark Wigmore

RE: MASTER SERVICES AGREEMENT - LETTER AGREEMENT

Gentlemen:

Reference is made to the Master Services Agreement, dated as of November 1,
2002, (the "Agreement") between The St. Paul Companies, Inc. ("St. Paul") and
Platinum Underwriters Holdings, Ltd. ("Platinum"). Capitalized terms used but
not defined herein have the meanings specified in the Agreement.

This letter confirms the agreement between St. Paul and Platinum to modify the
Agreement by (i) extending the Maximum Service Period for the Services provided
by St. Paul or its Post-closing Subsidiaries from June 30, 2003 until June 30,
2004; and (ii) revising the schedule of Services to be provided by St. Paul or
its Post-closing Subsidiaries.

The Agreement shall expire June 30, 2004, subject to the provisions of Section
1(c) of the Agreement. In addition, St. Paul or its Post-closing Subsidiaries
shall provide to Platinum or its Post-closing Subsidiaries each of the Services
specified on Schedule A (Revised) hereto, subject to the provisions of Section
1(f) of the Agreement. All other terms and conditions of the Agreement will
remain in full force and effect.

Sincerely,

PLATINUM UNDERWRITERS HOLDINGS, LTD.

By: /s/ Gregory E.A. Morrison
    -------------------------------------
    Gregory E.A. Morrison
    President and Chief Executive Officer

ACKNOWLEDGED, ACCEPTED AND AGREED:

THE ST. PAUL COMPANIES, INC.

By: /s/ Mark Wigmore
    --------------------------------------
    Mark Wigmore
    Senior Vice President

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SCHEDULE A (Revised)

         1.       Claim processing and payment for all business written on St.
                  Paul paper and subject to the Quota Share Retrocession
                  Agreements (as such term is defined in the Formation and
                  Separation Agreement).

         2.       Billing and collection services for balances due to/from from
                  brokers and cedants for all business written on St. Paul paper
                  and subject to the Quota Share Retrocession Agreements.

         3.       Processing, billing and collection services for all
                  retrocessional premium and loss inuring to the benefit of
                  Platinum for all business written on St. Paul paper subject to
                  the Quota Share Retrocession Agreements.

         4.       Provision of historical underwriting data with respect to the
                  experience of the St. Paul Re division of St. Paul in format
                  to be prescribed by Platinum.

         5.       Provision of ongoing underwriting data with respect to the
                  business ceded to Platinum under the Quota Share Retrocession
                  Agreements.

         6.       Access to or the actual reserving triangles at a reserving
                  class level.

         7.       Accounting guidance for Non-traditional accounts before a
                  commitment is made by Platinum to write the business.