Avro 504K biplane D7560 with 130hp Clerget engine, c 1917.

The Avro 504 first appeared in 1913 and was in service with the Royal Flying Corps during World War I. As early as November 1914, three 504s carried out a 'mas' bombing raid on German airship construction sheds at Friedrichshafen. In 1915 the Avro was adapted for training duties and remained in this role until the late 1920s.