The house flag of the Avenue Shipping Co. Ltd, London. On a rectangular white field, there is a blue cross with a blue bordered white diamond in the centre, bearing the blue letter 'A'. The flag is made of a wool and synthetic fibre bunting. It has a cotton hoist and is machine sewn. A rope and two Inglefield clips are attached.

Avenue Shipping was formerly the ship owning side of Birt, Potter & Hughes and called after their address: 2, Fenchurch Avenue. In 1954 the New Zealand Shipping Company formed a new 'Avenue Shipping' within its parent company P&O and took over the house flag of the older firm. The first Chairman was W.C. How the Deputy Chairman of New Zealand Shipping. The new company was floated on the stock exchange, where 1,500,000 shares were sold at £1 per share. In the first Annual report on 30 September 1955 there was a loss of about £50,000 during the year.
The Avenue Shipping Co. inherited four cargo vessels from NZS ('Antrim', 'Armagh', 'Limerick' and 'Tyrone'), and it had a 5th vessel ('Donegal') on order.

W. C. How retired in 1961, and C.A.W. Dawes was elected Chairman of the Board. Between 1957 and 1969 the fleet declined from seven ships with two building to only two vessels. Ownership passed to P&O General Cargo Division in 1971 and the house flag went out of use.