The house flag of the British Tanker Co. Ltd, London. On a white background, there is a red cross with a green diamond in the centre bearing a gold lion passant gardant. This design was in use from 1927 to 1955 and the central lion symbolized the Company's Iranian interests. The flag is made of a wool and synthetic fibre bunting. It has a cotton hoist and is machine sewn. The flag's design is painted. A rope and two Inglefield clips is attached.

British Petroleum was formed as the Anglo-Persian Oil Company in 1909 to exploit oil deposits in Persia. The British Tanker Co. Ltd started in 1915 to handle sea transport and achieve a contained, integrated oil company. The parent group, British Petroleum, was re-named the Anglo-Iranian Oil Company in 1935. In 1951 the company's Iranian assets were nationalized, a crisis partly resolved by negotiation in 1954 when the company was re-named British Petroleum. During the 1970s BP extended its oil interests to the North Sea and Alaska and now is a very large multinational group.