The Excelsior company could trace its history back to 1874 as a manufacturer of ordinary bicycles and were one of Britain's pioneer motorcycle manufacturers building their first motorcycle in 1896. Historically they had always been involved in motorcycle competition securing numerous successes at Brooklands and winning the 1929 Lightweight TT. For 1933 the company introduced a new machine for competition use featuring a twin high cam single cylinder engine with a radial four valve head and twin carburettors built specially for the company by Blackburne, dubbed the Mechanical Marvel it won the 1933 TT but quickly gained a reputation for being hard to keep in tune and was dropped at the end of the 1934 season to be replaced by a machine that secured Excelsior's reputation. The new model, named the Manxman was initially available in 246cc and 346cc sharing a common stroke with a 496cc version being added to the range for the 1936 season. The single overhead cam, single cylinder engine employed dry sump lubrication and was mechanically straightforward and robust. For the first seasons production both models were initially offered with full road equipment, however, by the time that the 500cc class version was added to the range dedicated racing versions were offered alongside the road legal variants. The 1937 season 250 and 350cc versions benefited from Excelsior's competition activities, adopting new short stroke engine dimensions as used by the works machines in addition to an improved lubrication system. The 500cc version was joined by a "super sports" variant fitted with a bronze head, close ratio gears a competition mag-dyno and quickly detachable lighting system. Little changed for 1938 but for 1939 the range adopted hairpin valve springs and in the case of the racing variants the gearbox was mounted directly to the crankcase with power being taken from the crankshaft sprocket to the gearbox by a duplex primary drive.
The example of the rare 500cc class Manxman