Private company

Williamson Flat Twin

Logo: Buch-t, CC BY-SA 3.0 de, via Wikimedia Commons3

Type of motorcycle

The Williamson Flat Twin was motorcycle made in Coventry, UK by William ('Billy') Williamson, who had been managing director of the Coventry-based Rex company. He teamed up with William Douglas (of Douglas Motorcycles to develop new prototype motorcycles under the name Williamson-Douglas and employed Billy's brother Harold as a test rider. Douglas had been developing a 964 cc water-cooled flat twin engine that could be used either for light cars or motorcycles.2 It ceased to exist in 1920.1 Wikipedia text CC BY-SA 4.0

Last updated Oct 21, 2026.

Overview

1912Founded1
  • Industryautomobile manufacturer1
  • HeadquartersCoventry1
  • Legal formpublic limited company1
1913 Williamson Flat Twin motorcycle
Photo: TR001, CC BY-SA 3.0, via Wikimedia Commons4

The Williamson Flat Twin was motorcycle made in Coventry, UK by William ('Billy') Williamson, who had been managing director of the Coventry-based Rex company. He teamed up with William Douglas (of Douglas Motorcycles to develop new prototype motorcycles under the name Williamson-Douglas and employed Billy's brother Harold as a test rider. Douglas had been developing a 964 cc water-cooled flat twin engine that could be used either for light cars or motorcycles. Billy Williamson fitted this engine into a frame with Douglas-Druid girder forks and a Douglas two-speed gearbox and a foot-operated clutch which was launched in 1912 at a cost of £82. In 1913 an air-cooled version was added to the range and in 1914 a kick starter was added. Production was halted by World War I and in 1919 the only engines available were JAP 980 cc air-cooled side valves, so Williamson redesigned the frame to fit. Unfortunately Billy Williamson suffered a fatal heart attack in 1920 after only twenty motorcycles had been produced.2

Timeline

  1. 1920Dissolved Dissolved1
  2. 1912Founded Founded1

Sources

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