OneBeacon Appoints Southern Marine & Aviation Inc.

OneBeacon Insurance Group announced today that it has signed an agreement with Southern Marine & Aviation Inc., to represent its International Marine Underwriters (IMU) division. Under the agreement, IMU will assume the new and renewal business written under a primary marine cargo program managed by Southern Marine & Aviation, effective January 1, 2008.

Based in Houston, Southern Marine & Aviation is a marine-specialty Managing General Agent with more than 50 years of experience and expertise in writing commercial marine and cargo insurance. It is a division of Crump Insurance Services, Inc., and a recognized leader in the underwriting of petroleum and bulk liquid cargo insurance. Southern Marine & Aviation has the capability to write cargo interests up to $50 million.

"This partnership with Southern Marine & Aviation will provide synergies and complement the other lines of business we write," said Robert Gallagher, President of International Marine Underwriters. "In addition, combining the two books of ocean cargo business will position IMU as a market leader in the U.S."

International Marine Underwriters is a division of OneBeacon Insurance Group, which is rated A (excellent) by A.M. Best. IMU is headquartered in New York City and offers ocean marine solutions for hull, marine liabilities, and private-pleasure yachts, as well as ocean cargo.

OneBeacon Insurance Group's operating subsidiaries offer a range of specialty and segmented commercial and personal insurance products sold primarily through select independent agents. As one of the oldest property and casualty insurers in the United States, OneBeacon traces its roots to 1831 and the Potomac Fire Insurance Company. Today, OneBeacon's specialty insurance products are available countrywide, and commercial and personal lines are offered in select geographic territories.

OneBeacon's principal business office is in Canton, Massachusetts. The company is publicly traded on the New York Stock Exchange under the symbol (NYSE:OB) .

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995

This press release may contain "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements, other than statements of historical facts, included or referenced in this release which address activities, events or developments which we expect or anticipate will or may occur in the future are forward-looking statements. The words "will," "believe," "intend," "expect," "anticipate," "project," "estimate," "predict" and similar expressions are also intended to identify forward-looking statements. These forward-looking statements include, among others, statements with respect to OneBeacon:

-- growth in book value per share or return on equity;
-- business strategy;
-- financial and operating targets or plans;
-- incurred loss and loss adjustment expenses and the adequacy of its loss
and loss adjustment expense reserves and related reinsurance;
-- projections of revenues, income (or loss), earnings (or loss) per
share, dividends, market share or other financial forecasts;
-- expansion and growth of our business and operations; and
-- future capital expenditures.


These statements are based on certain assumptions and analyses made by OneBeacon in light of its experience and perception of historical trends, current conditions and expected future developments, as well as other factors believed to be appropriate in the circumstances. However, whether actual results and developments will conform to our expectations and predictions is subject to a number of risks and uncertainties that could cause actual results to differ materially from expectations, including:

-- claims arising from catastrophic events, such as hurricanes,
earthquakes, floods or terrorist attacks;
-- recorded loss and loss adjustment expense reserves subsequently proving
to have been inadequate;
-- the continued availability and cost of reinsurance coverage;
-- the continued availability of capital and financing;
-- general economic, market or business conditions;
-- business opportunities (or lack thereof) that may be presented to it
and pursued;
-- competitive forces, including the conduct of other property and
casualty insurers and reinsurers;
-- changes in domestic or foreign laws or regulations, or their
interpretation, applicable to OneBeacon, its competitors or its
clients;
-- an economic downturn or other economic conditions adversely affecting
its financial position;
-- other factors, most of which are beyond OneBeacon's control; and
-- the risks that are described from time to time in OneBeacon's filings
with the Securities and Exchange Commission, including but not limited
to OneBeacon's Annual Report on Form 10-K for the fiscal year ended
December 31, 2006 filed February 28, 2007.