Lt. Col. G. le Q Martel saw Russian BT tanks in maneuvers and suggested the war office adopt the Christie suspension. Morris Commercial Ltd. built prototypes based on two Christie tanks purchased in 1936.
The speed was governed down from 35 mph to 30 mph, alterations in the clutch and transmission, and using shorter pitched tracks. The engine could be started with compressed air or electronically.
Used same turret as the A9 but with larger commander's cupola.