Siddeley Deasy Motor Car Co. Ltd
In 1909, J. D. Siddeley resigned from Wolseley and took over the Deasy Motor Co and the company became known as Siddeley-Deasy. During World War I the company produced trucks, ambulances, and staff cars. In 1915 airframes and aero-engines started to be produced as well.
Major F.M. Green served as chief engineer at the Royal Aircraft Factory and then become a part of the Siddeley-Deasy Motor Car Company. Not limited to the production of motor vehicles, the Siddeley-Deasy brand also delved into manufacture of engines and aircraft. The company was based out of Coventry and was founded by Henry Hugh Peter Deasy. While Deasy left in 1908, J D Siddeley came aboard and changed the company name to Siddeley-Deasy. From there, the company would gradually morph into the Armstrong Whitworth Aircraft firm (known formally as the Sir W.G. Armstrong Whitworth Aircraft Co. Ltd after their 1920 merger with Armstrong Whitworth) and became responsible for a large portion of Siskin production thereafter.
In April 1919 Siddeley-Deasy was bought out by Armstrong Whitworth Development Company of Newcastle upon Tyne and in May 1919 became Armstrong Siddeley Motors Ltd a subsidiary with J. D. Siddeley as Managing Director.
Based at Coventry, Warwickshire; was concerned in production of RAF R.E.7 and R.E.8 and Airco D.H.10 during First World War. Own experimental types included R.T.1 of 1917-1918, a redesigned R.E.8; S.R.2 Siskin, developed from ideas of Major F. M. Green and precursor of famous Armstrong Whitworth line of fighters; and Sinaia twin-engined bomber, completed 1921, also associated with Armstrong Whitworth. In 1919 Armstrong Whitworth and Siddeley-Deasy combined to form in 1920 Sir W. G. Armstrong Whitworth Aircraft Ltd.