In early 1916, the British
War Office drew up a specification for a multi-seat escort fighter to be powered by one of the new
Rolls-Royce Eagle engines, intended to protect formations of bombers from German fighters, with an additional role of destroying enemy
airships. While the specification did not require high speed, a good field of fire for its guns was essential, while the secondary anti-Zeppelin role demanded an endurance of at least seven hours. It had three-bay, narrow chord wings, with the streamlined nacelle housing the upper gunner who was armed with a
Lewis gun built around the centre section of the upper wing.
Ailerons were fitted to all wings, with
air brakes fitted to the lower wing. The deep
fuselage housed the pilot and a second gunner to guard the aircraft's tail. Balancing wheels were fitted well ahead of the aircraft's mainwheels in order to prevent the aircraft overturning, as the upper gunner would be extremely vulnerable if this occurred. The prototype, which was nicknamed "Egg-Box", flew late in 1916. ==Specifications (L.R.T.Tr.)==