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of Bristol, maker of engines, motorcycles and trucks
1947-1950 Douglas launched various new models of motorcycle.
1948 Douglas was again in economic distress and forced to rationalize its line of motorcycles to a series based on a 350cc flat twin.
1951 A 500cc prototype was shown but never made. An agreement was made for the company to build the Italian Vespa scooter under licence.
1955 The last model made was the advanced and novel 350cc Dragonfly. Distinctive looks and good handling could not hide the low top speed (75mph, although a sports model claimed 84mph) and poor low-rev performance.
1956 The firm was taken over by Westinghouse Brake and Signal Co.
1957 The Vespa was still imported, but the end of the Douglas model was close.
1958 Made a loss due to poor sales of the scooter.
1959 Subsidiary of Westinghouse Brake and Signal Co; producing large quantities of Westinghouse automotive brakes for commercial vehicles, and pneumatic control equipment for industrial and marine uses.
1961 Subsidiary of Westinghouse Brake and Signal Co. Light engineers and metal founders. Manufacturer of Vespa motor scooters, road brakes, and signal and colliery equipment. Employs 2,000 persons (Probably figures for the holding company) 
1961 Light engineers and metal founders, specialising in the manufacture of Vespa Motor Scooters, Road Brakes and Signal and Colliery Equipment. 2,000 employees.
Note: For many years afterwards, still trading under the Douglas name, the company imported Gilera mopeds and lightweight motorcycles.