Williamson Motor Co
Williamson Motor Co of Earlsdon, Coventry. Also as A. Williamson and Co.
Maker of cars from 1913 and motorcycles produced from 1912 to 1920.
1912 The first machine made it debut and offered power with silence, and no vibration, courtesy of its 8hp flat-twin water-cooled engine, made for them by Douglas of Bristol. As it was part of their stationary engine range, it had a starting handle, like that of a car. It was a typical Douglas engine with side valves, gear-driven magneto and was installed low down in a long frame to drive a two-speed Douglas gearbox with all-chain drive.
1913-1917 For a list of the models and prices of cars see the 1917 Red Book
1913-1917 For a list of the models and prices of motorcycles see the 1917 Red Book
1913 An air-cooled version was added, but it did not sell as well as the quieter machine and had a tendency to over-heat. It did, however, continue to be offered as an option. Most models sold were water-cooled and used for sidecars.
1916 Production continued until that year, and then stopped until after the War.
1920 Only the V-twin remained, this being sold with the sidecar as a complete combination. It was their final year of production.
1932 Company listed to be struck off 
Sources of Information
-  Gazette Issue 33862 published on the 9 September 1932. Page 11 of 72
- The British Motorcycle Directory - Over 1,100 Marques from 1888 - by Roy Bacon and Ken Hallworth. Pub: The Crowood Press 2004 ISBN 1 86126 674 X
-  MICMA Web Site
-  Ian Chadwick's motorcycle web site
-  Miscellaneous A-Z Classic and Vintage Motorcycles web site
- The Encyclopedia of the Motorcycle by Peter Henshaw. Published 2007. ISBN 978 1 8401 3967 9