FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * WHITE MOUNTAINS INSURANCE GROUP LTD   2. Issuer Name and Ticker or Trading Symbol MONTPELIER RE HOLDINGS LTD [MRH] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 80 SOUTH MAIN STREET 3. Date of Earliest Transaction (Month/Day/Year) 03/08/2005 (Street) HANOVER, NH 03755 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Shares 03/08/2005   J(1)   3,063 A $ 41.78 9,189 I By Folksamerica Reinsurance Company (2) Common Shares               3,600,000 I By OneBeacon Insurance Company (2) Common Shares               900,000 I By OneBeacon Insurance Group LLC (2) Common Shares               1,800,000 I By Pennsylvania General Insurance Company (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Warrant Shares

$ 16.67 (3)

(4)

01/03/2012

Common Shares

7,172,357.5

7,172,357.5

I

By wholly-owned subsidiaries of White Mountains Insurance Group, Ltd. See Footnote 5. (5)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
WHITE MOUNTAINS INSURANCE GROUP LTD 80 SOUTH MAIN STREET HANOVER, NH 03755		X

Signatures

Dennis Beaulieu, Corporate Secretary, White Mountains Insurance Group, Ltd.		03/08/2005
**Signature of Reporting Person		Date
Dennis Beaulieu, by Power of Attorney on behalf of Folksamerica Reinsurance Company		03/08/2005
**Signature of Reporting Person		Date
Dennis Beaulieu, by Power of Attorney on behalf of OneBeacon Insurance Group, LLC, OneBeacon Insurance Company, and Pennsylvania General Insurance Company		03/08/2005
**Signature of Reporting Person		Date
Dennis Beaulieu, by Power of Attorney on behalf of White Mountains Holdings Bermuda Ltd.		03/08/2005
**Signature of Reporting Person		Date
Dennis Beaulieu, by Power of Attorney on behalf of Sirius International Insurance Corporation		03/08/2005
**Signature of Reporting Person		Date
Dennis Beaulieu, on behalf of White Mountains Financial Services Ltd.		03/08/2005
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Pro rata distribution from Century Capital Partners LP, of which Folksamerica Reinsurance Company, an indirect wholly-owned subsidiary of White Mountains Insurance Group, Ltd., is a limited partner.
(2)	Folksamerica Reinsurance Company, OneBeacon Insurance Company, The Camden Fire Insurance Association, and Pennsylvania General Insurance Company are indirect wholly-owned subsidiaries of White Mountains Insurance Group, Ltd.
(3)	Warrants Shares are exercisable for Common Shares on a 1 for 1 basis at an exercise price of $16.67 per Warrant Share.
(4)	Currently exercisable.
(5)	Warrant Shares are held by Folksamerica Reinsurance Company, White Mountains Holdings Bermuda Ltd., Sirius International Insurance Corporation and White Mountains Financial Services Ltd., each an indirect wholly-owned subsidiary of White Mountains Insurance Group, Ltd.

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