Avro 504K biplane D7560 with 130hp Clerget engine, c 1917.
© Science Museum / Science & Society Picture Library
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 'mass' bombing raid on German airship construction sheds at Friedrichshafen. In 1915 the Avro was ad