In 1957 the last of the Auster liason aircraft were retired from the Royal Air Force with great reluctance. The British Army, however, keen to replace the unique capabilities of the Auster with the de Havilland Beaver, came up against a government limit on the size of aircraft the Army Air Corps could operate- 4000 lbs. Anything larger was to be operated by the RAF. However, the AAC wasn't deterred by this regulation and managed to get a waiver to allow them to order 46 DHC-2 Beavers delivered from 1960-1967. No other type of aircraft was even considered.
However, as early as 1952 de Havilland Canada was considering a British-built Beaver. The 550 horsepower Alvis Leonides radial, already in use with the Percival Provost and Percival Pembroke twin engine communications aircraft, offered 100 more horsepower for an additional weight of 98 lbs. One of the engines was shipped to de Havilland's plant in Downsview (Toronto) for testing on a Beaver. Aircraft CF-GOE-X was fitted with a longer nose cowling to accommodate the Leonides engine which drove a larger three-bladed propeller. The vertical fin required redesign with a taller design with straight leading and trailing edges and more dorsal fin fillet area.
The Leonides Beaver (also known as the Beaver Mk.2) first flew at Downsview on 10 March 1953 and demonstrated improvements in top speeds and time-to-climb. However, the cost of the conversion outweighed the additional performance and the British Army Air Corps ended up ordering standard Wasp Junior-powered Beavers. During flight testing in Britain, the AAC even landed one of their Beavers on a Royal Navy carrier deck.
Source: The Immortal Beaver- The World's Greatest Bush Plane by Sean Rossiter. Douglas & McIntyre, 1996, p104-106