House flag of Coast Lines Ltd, Liverpool. A rectangular flag with five horizontal stripes comprising blue at the top and bottom and a central red stripe between two white stripes. The blue letters 'CL' are placed across the centre. The flag is made of a wool and synthetic fibre bunting. It has a cotton hoist and is machine sewn. A rope and toggle is attached.

The company was founded by the merger of three Merseyside-based coasting firms in 1913. Under Sir Alfred Read, it took over most companies carrying cargo and passengers across the Irish Sea with the exception of those controlled by the railways. It also owned road haulage companies and was a pioneer in co-ordinating sea and road transport. Coast Lines expanded overseas into South African coastal shipping between 1949 to 1966. It was slow to acquire passenger ferries and went into a decline after the Second World War. The firm was taken over by P&O in 1971.