The Douglas Mark III is a British motorcycle designed and built by Douglas motorcycles in Bristol between 1948 and 1949. The 350 cc flat twin engine in the Douglas Mark III was based on a Second World War electricity generator. As well as the 1948-9 Douglas Mark III, Douglas also produced a Mark III "De Luxe", a Mark III Sports, and a rigid-framed motorcycle trials Competition version. History During the Second World War the Bristol-based Douglas motorcycle company produced stationary generator engines using their 348 cc overhead valve flat twin. One of these Douglas generators was used at Winston Churchill's wartime summit meeting held next to the Sphinx in Giza. By the end of the war in 1945, Douglas restarted motorcycle production – much to the surprise of the industry, as it was generally expected that the war had led to other interests, with the company being taken over by Aero Engines Ltd, so there were not many engineering staff left for the development of new motorcycles. The Douglas T35 used the same flat-twin 350 cc as the generator, mounted in a duplex fame with torsion bar rear suspension. The T35 was an unexpected export success; 1947 factory records show them being exported to Canada, Switzerland, Belgium, Santiago, and Russia. Development In 1948, the company developed a series of motorcycles based on the T35. Designed by George Halliday, these featured Douglas "Radialraulic" forks with the front wheel spindle carried on short leading links pivoted at the rear of the fork stanchions – with springs and a damping mechanism inside the stanchions. Although the frame and suspension were innovative, the engine was essentially a generator, designed to run for long periods at a steady speed and it did not cope well with the varying engine speeds of motorcycling. There was also a tendency to sideways shaking at low engine speeds which was a feature of the horizontally opposed engine. Douglas hired former Sunbeam motorcycles designer Erling Poppe as Technical Director, Freddie Dixon as their specialist engine tuner and Walter Moore (who designed the Norton CS1) as Works Superintendent. The result was the 1949 Douglas Mark III, which had improved performance through an uprated cylinder head, combustion chambers, and pistons. Douglas also produced a Mark III "De Luxe", a Mark III Sports, and a rigid-framed motorcycle trials Competition version with high-level exhausts and a less deeply valanced front mudguard. There never was