The Williamson Motor Co. Ltd., 26 Moor Street, Coventry.
Williamson motorcycles were produced at the Cromwell Works in Earlsdon from 1912 to 1920 by William "Billy" Williamson aided by his brother Harry after they left Rex due to a dispute with the Pilkington brothers, the founders of the company. At the time Billy was managing director and Harry was sales manager. Harry moved to Singer and took up the same role there, whilst Billy set up shop in the old Clarendon Motor Works premises at 77 Moor Street Earlsdon, a five minute walk from Rex at the other end of the street. He was supported in this venture by relations who owned the Douglas concern in Bristol. William had joined the industry in 1892, working with Allard which was absorbed by Rex.
1912. The first machine made its debut and offered power with silence, and no vibration, courtesy of its 8hp 946cc flat-twin water-cooled engine, made for them by Douglas. As with their their stationary engine range, on which it was based, it had a starting crank handle like that of a car. It was a typical Douglas HO twin engine with side valves and gear-driven magneto, and was positioned low in a long frame to drive a two-speed Douglas gearbox with all-chain drive.
1913. An air-cooled version of the horizontally opposed longitudinal twin 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.
1919. Late in the year they returned with the air-cooled flat-twin. They also built two prototypes using the 770cc sidevalve JAP V-twin engine and three-speed Sturmey-Archer gearbox with all chain drive, all housed in a new frame. The reasoning behind this was that they were concerned about supply of the Douglas engines.
1920. On Friday 20th February  Billy wrote to Harry, who was in France chasing business, "I have not managed to make the time to see Dr. Stephens again about my chest pains but dear Martha is saying I must go soon. The tablets help keep them at bay for most of the time." Later that year Billy Williamson died of a heart attack.
In total some 20 motorcycles were built, including the two JAP prototypes. The company also built automobiles from 1913 to 1916.
Notes1. One source says that the 946cc Douglas engines were made "exclusively" for Williamson. Yesterdays mentions that they may be industrial generator engines built for Marconi Wireless, or that they may have been built for use in a Douglas cyclecar.
Sources:Graces Guide; National Motorcycle Museum UK; earlsdon.org.uk; historiccoventry.co.uk; Martin Shelley.
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