White Mountains Insurance (WTM) SC TO-I Issuer tender offer statement

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Exhibit (a)(1)(C)

NOTICE OF GUARANTEED DELIVERY
(Not to be used for Signature Guarantee)

WHITE MOUNTAINS INSURANCE GROUP, LTD.

THE OFFER, PRORATION PERIOD AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY TIME, ON MARCH 22, 2012, UNLESS THE OFFER IS EXTENDED (SUCH DATE AND TIME, AS THEY MAY BE EXTENDED, THE "EXPIRATION DATE").

        As set forth in Section 2 of the Offer to Purchase (as defined below), this form (or a manually executed facsimile hereof) must be used to accept the Offer (as defined below) if (1) certificates evidencing your tendered Common Shares of White Mountains Insurance Group, Ltd. (the "Company"), par value of $1.00 per share (the "Shares"), are not immediately available or cannot be delivered to the Depositary before the Expiration Date (as defined in the Offer to Purchase), (2) the procedures for book-entry transfer described in Section 2 of the Offer to Purchase cannot be completed before the Expiration Date or (3) time will not permit all required documents to reach the Depositary before the Expiration Date. This form, signed and properly completed, may be delivered to Computershare Trust Company, N.A. (the "Depositary") by mail or overnight delivery or transmitted by facsimile to the Depositary. See Section 2 of the Offer to Purchase.

The Depositary for the Offer is:

Computershare Trust Company, N.A.

By First Class, Registered or
Certified Mail:
Computershare Trust Company,
N.A., Depositary
c/o Voluntary Corporate Actions
PO Box 43011
Providence, Rhode Island
02940-3011 For Delivery of Notice of
Guaranteed Delivery via Facsimile:
(617) 360-6810

To confirm receipt of FAX, call
(781) 575-2332 By Express or Overnight Delivery:
Computershare Trust Company,
N.A., Depositary
c/o Voluntary Corporate Actions
250 Royall Street, Suite V
Canton, Massachusetts 02021

DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS OTHER THAN SHOWN ABOVE OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE NUMBER OTHER THAN THE ONE LISTED ABOVE WILL NOT CONSTITUTE A VALID DELIVERY. DELIVERIES TO THE COMPANY, THE INFORMATION AGENT OR THE DEPOSITORY TRUST COMPANY ("DTC") WILL NOT BE FORWARDED TO THE DEPOSITARY AND WILL NOT CONSTITUTE VALID DELIVERY.

THIS NOTICE OF GUARANTEED DELIVERY IS NOT TO BE USED TO GUARANTEE SIGNATURES. IF A SIGNATURE ON A LETTER OF TRANSMITTAL IS REQUIRED TO BE GUARANTEED BY AN ELIGIBLE INSTITUTION (AS DEFINED IN THE OFFER TO PURCHASE) UNDER THE INSTRUCTIONS TO THE LETTER OF TRANSMITTAL, SUCH SIGNATURE GUARANTEE MUST APPEAR IN THE APPLICABLE SPACE PROVIDED IN THE SIGNATURE BOX ON THE LETTER OF TRANSMITTAL.

Ladies and Gentlemen:

        The undersigned hereby tenders to the Company, upon the terms and subject to the conditions set forth in its Offer to Purchase dated February 24, 2012 (the "Offer to Purchase"), and in the related Letter of Transmittal (which together, as they may be amended or supplemented from time to time, constitute the "Offer"), receipt of which is hereby acknowledged, the number (indicated herein) of the Shares listed below pursuant to the guaranteed delivery procedures set forth in Section 2 of the Offer to Purchase.

NUMBER OF SHARES TO BE TENDERED:            SHARES
Certificate Nos. (if available):                                    

ODD LOTS
(See Instruction 7 of the Letter of Transmittal)

        As described in Section 1 of the Offer to Purchase, under certain conditions, a shareholder owning beneficially or of record an aggregate of fewer than 100 Shares and who tenders all such Shares and satisfies the other requirements set forth in the Offer to Purchase, may have his or her Shares accepted for payment before any proration of other tendered Shares. This preference is not available to partial tenders, or to beneficial or record holders of an aggregate of 100 or more Shares, even if these holders have separate accounts representing fewer than 100 Shares. Accordingly, this section is to be completed only if Shares are being tendered by or on behalf of a person owning, beneficially or of record, an aggregate of fewer than 100 Shares. The undersigned either (check one box):

o

owns, whether beneficially or of record, an aggregate of fewer than 100 Shares and is tendering all such Shares; or

o

is a broker, dealer, commercial bank, trust company, or other nominee that (a) is tendering for the beneficial owner(s), Shares with respect to which it is the record holder, and (b) believes, based upon representations made to it by the beneficial owner(s), that each such person is the beneficial owner of an aggregate of fewer than 100 Shares and is tendering all such Shares.

SIGN HERE

Name(s) of Record Holder(s):
	(Please Type or Print)

Address(es):
	(Include Zip Code)

Area Code and Telephone Number:

Taxpayer ID No(s). or Social Security No(s).:

Account Number (at The Depository Trust Company):

Date:

Signature(s):

If Shares will be tendered by book-entry transfer, check this boxo and provide the following information:

Name of Tendering Institution:

Account Number at Book-Entry Transfer Facility:

Transaction Code Number:

GUARANTEE
(Not to be used for signature guarantee)

The undersigned, a financial institution that is a participant in the Securities Transfer Agent Medallion Program, the New York Stock Exchange Medallion Signature Program or the Stock Exchange Medallion Program, hereby guarantees (i) that the above-named person(s) has a net long position in the Shares being tendered within the meaning of Rule 14e-4 promulgated under the Securities Exchange Act of 1934, as amended, (ii) that such tender of Shares complies with Rule 14e-4 and (iii) to deliver to the Depositary at one of its addresses set forth above certificate(s) for the Shares tendered hereby, in proper form for transfer, or a confirmation of the book-entry transfer of the Shares into the Depositary's account at The Depository Trust Company, together with a properly completed and duly executed Letter of Transmittal, with any required signature guarantees, or an Agent's Message (as defined in the Offer to Purchase) in the case of a book-entry transfer, and any other required documents, within three New York Stock Exchange trading days after the date of receipt by the Depositary.

The eligible institution that completes this form must communicate the guarantee to the Depositary and must deliver the Letter of Transmittal or an Agent's Message (as defined in the Offer to Purchase) and certificates for shares to the Depositary or complete the procedures for book-entry transfer deliveries within the time period set forth herein. Failure to do so could result in financial loss to such eligible institution.

Name of Firm:		Address:
(Authorized Signature)		(Zip Code)
Name:		Area Code and Telephone No.:
	(Please Print)
Title:		Dated:

THIS FORM IS NOT TO BE USED TO GUARANTEE SIGNATURES. IF A SIGNATURE ON A LETTER OF TRANSMITTAL IS REQUIRED TO BE GUARANTEED BY AN ELIGIBLE INSTITUTION UNDER THE INSTRUCTIONS THERETO, SUCH SIGNATURE GUARANTEE MUST APPEAR IN THE APPLICABLE SPACE PROVIDED IN THE SIGNATURE BOX ON THE LETTER OF TRANSMITTAL.

DO NOT SEND SHARE CERTIFICATES WITH THIS FORM. YOUR SHARE CERTIFICATES MUST BE SENT WITH THE LETTER OF TRANSMITTAL.

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Exhibit (a)(1)(C)

GUARANTEE (Not to be used for signature guarantee)