From Wiki so.......:
"After the war, the company attempted to produce aircraft for the civil market based on their wartime types, such as the Dove derivative of the Pup and the Swallow, a single-winged Camel, but the wide availability of war-surplus aircraft at knock-down prices meant this was never economic. In 1919 the company worked with ABC motorcycles and produced 400cc flat twin motorcycles under licence. They also purchased ABC Motors in an attempt to diversify, but this venture also failed. The Sopwith company was wound up in 1920 after the business collapsed, and in the face of a potential large demand from the government for Excess War Profits Duty.[citation needed] The remaining lease on the Ham factory was sold to Leyland Motors.[4]
Upon the liquidation of the Sopwith company, Tom Sopwith himself, together with Harry Hawker, Fred Sigrist and Bill Eyre, immediately formed H.G. Hawker Engineering, forerunner of the Hawker Aircraft and Hawker Siddeley lineage"