The 1930 London Naval Treaty tightly limited an auxiliary's speed, armament, aircraft equipment, and ability to receive or operate aircraft. The 1936 text doubled the allowance of guns above three inches from four to eight and raised the speed ceiling from 20 to 28 knots, enough for a vessel to remain near a battle fleet. It also removed the explicit ban on receiving aircraft from the air and the three-aircraft operating limit. The remaining language prohibited a ship designed primarily to operate aircraft, but did not prevent one designed primarily to maintain them. Henderson and Director of Naval Construction Stanley Goodall could therefore describe a fast, flight-deck-equipped aviation support ship as an unrestricted auxiliary rather than a carrier.
Chapter · 5:10-11:25
Auxiliary rules open a path for HMS Unicorn
Changes between the 1930 and 1936 treaty definitions leave room for a fast aviation-support vessel with a flight deck.