The four prototypes and first production batch of six aircraft were built at Cricklewood, with the first aircraft delivered by road to Hendon on 9 December 1915. The first flight of the prototype, was made at Hendon on 17 December, when a short straight flight was made, the aircraft taking off without trouble at . A second flight was made the following day, when it was found that the aircraft would not fly faster than about . This was blamed on the drag caused by large honeycomb radiators, which were changed to tube radiators mounted on either side of the engine nacelles. A third flight on 31 December revealed a number of control problems, the ailerons and elevators were effective but heavy, partly due to excessive friction in the control circuit and the rudders were seriously overbalanced. After minor modifications, the aircraft was flown to RNAS Eastchurch, where full-speed trials were made. On reaching , the tail unit began to vibrate and twist violently; the pilot immediately landed and an inspection showed severe damage to the rear fuselage structure. Reinforcement failed to cure the problem, meanwhile the enclosed cockpit and most of the armour plating were also removed. The second prototype was completed in April 1916 and had an open cockpit in a longer nose with room for a gunner. To save weight, most of the armour was deleted and was the arrangement for later production of the machine.