Exhibit 25.3

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM T-1

STATEMENT OF ELIGIBILITY UNDER THE TRUST

INDENTURE ACT OF 1939 OF A CORPORATION

DESIGNATED TO ACT AS TRUSTEE

CHECK IF AN APPLICATION TO DETERMINE ELIGIBILITY OF A TRUSTEE PURSUANT TO SECTION 305(b)(2) x

THE BANK OF NEW YORK MELLON TRUST COMPANY,

NATIONAL ASSOCIATION

(Exact name of trustee as specified in its charter)

Rhea L. Picard, Legal Department

The Bank of New York Mellon Trust Company, National Association

400 South Hope Street, Suite 400

Los Angeles, California 90017

(213) 630-6476

(Name, address and telephone number of agent for service)

ONEBEACON U.S. HOLDINGS, INC.

(Exact name of obligor as specified in its charter)

Senior Notes

(Title of the indenture securities)

GUARANTOR

Item 1.   General Information.

Furnish the following information as to the Trustee:

(a)   Name and address of each examining or supervising authority to which it is subject.

Comptroller of the Currency – United States Department of the Treasury, Washington, D.C. 20219

Federal Reserve Bank, San Francisco, California 94105

Federal Deposit Insurance Corporation, Washington, D.C. 20429

(b)   Whether it is authorized to exercise corporate trust powers.

Yes.

Item 2.    Affiliations with the Obligor.

If the obligor is an affiliate of the trustee, describe each such affiliation.

None.

Pursuant to General Instruction B of Form T-1, no responses are included for Items 3-15 of Form T-1 because the Obligor is not in default as provided under Item 13.

Item 16.   List of exhibits.

Exhibits identified in parentheses below, on file with the Commission, are incorporated herein by reference as exhibits hereto, pursuant to Rule 7a-29 under the Trust Indenture Act of 1939 (the “Act”) and 17 C.F.R. 229.10(d).

1.                                      A copy of the articles of association of The Bank of New York Mellon Trust Company, National Association. (Exhibit 1 to Form T-1 filed on September 8, 2008 in connection with Registration Statement No. 333-135006).

2.                                      A copy of certificate of authority of the trustee to commence business. (Exhibit 2 to Form T-1 filed on January 11, 2005 in connection with Registration Statement No. 333-121948).

3.                                      A copy of the authorization of the trustee to exercise corporate trust powers. (Exhibit 3 to Form T-1 filed on September 8, 2008 in connection with Registration Statement No. 333-135006).

4.                                      A copy of the existing by-laws of the trustee. (Exhibit 4 to Form T-1 filed on October 28, 2009 in connection with Registration Statement No. 333-162713).

6.                                      The consent of the trustee required by Section 321(b) of the Act.

7.                                      A copy of the latest report of condition of the trustee published pursuant to law or to the requirements of its supervising or examining authority.

SIGNATURE

Pursuant to the requirements of the Trust Indenture Act of 1939, the trustee, The Bank of New York Mellon Trust Company, National Association, a banking association organized and existing under the laws of the United States of America, has duly caused this statement of eligibility to be signed on its behalf by the undersigned, thereunto duly authorized, all in the City of Chicago, and State of Illinois on the 5th day of November, 2012.

THE BANK OF NEW YORK MELLON TRUST COMPANY,

NATIONAL ASSOCIATION

EXHIBIT 6

The consent of the Trustee required by Section 321(b) of the Trust Indenture Act of 1939

Securities and Exchange Commission

Washington, D.C.  20549

Ladies and Gentlemen:

In connection with the qualification of an indenture by and among OneBeacon Insurance Group, Ltd., OneBeacon U.S. Holdings, Inc. and The Bank of New York Mellon Trust Company, National Association, as trustee, the undersigned, in accordance with Section 321(b) of the Trust Indenture Act of 1939, as amended, hereby consents that the reports of examinations of the undersigned, made by Federal, State, Territorial, or District authorities, may be furnished by such authorities to the Securities and Exchange Commission upon its request therefor.

EXHIBIT 7

Consolidated Report of Condition of

THE BANK OF NEW YORK MELLON TRUST COMPANY, NATIONAL ASSOCIATION

of 400 South Hope Street, Suite 400, Los Angeles, CA 90071

At the close of business September 30, 2012, published in accordance with Federal regulatory authority instructions.

I, Karen Bayz, CFO and Managing Director of the above-named bank do hereby declare that the Reports of Condition and Income (including the supporting schedules) for this report date have been prepared in conformance with the instructions issued by the appropriate Federal regulatory authority and are true to the best of my knowledge and belief.

Karen Bayz          )               CFO and Managing Director

We, the undersigned directors (trustees), attest to the correctness of the Report of Condition (including the supporting schedules) for this report date and declare that it has been examined by us and to the best of our knowledge and belief has been prepared in conformance with the instructions issued by the appropriate Federal regulatory authority and is true and correct.