The house flag of British and Commonwealth Shipping Co. Ltd, London. A blue rectangular flag with a white-bordered red saltire and a white diamond bearing a red lion in the centre. The flag is made of a wool and synthetic fibre bunting. It has a cotton hoist and is machine sewn with the lion printed. A rope and toggle is attached.

In 1955, the Clan Line merged with the Union-Castle Line to form the British & Commonwealth Shipping Co. Ltd under the management of Cayzer, Irvine & Co. Ltd. The merger of these two large shipping companies and their subsidiary interests brought together the following ship owning companies: Bullard King & Co. Ltd, Houston Line Ltd, King Line Ltd, Scottish Tanker Co. Ltd, Clan Line Steamer Ltd, Scottish Shire Line Ltd and Union-Castle.

The fleet shrunk during the 1960s due to containers and bulk carriers coming into use in the general cargo and fluid transport trade. In 1973 the company merged with the South African Marine Corporation to become International Liner Services Ltd. They eventually withdrew from shipping in 1982 due to competition from air travel.