1912 - 1919
In 1909 Captain H.H.P. Deasy left the company he had founded his place being taken by J.D. Siddeley who had just left Wolseley. In 1910 he introduced his own designs a 2917cc 14hp and a 4082cc 18/28hp, known as Siddeley-J.D.S. They had dashboard radiators and the engines probably were supplied by Aster. A smaller four of 1944cc appeared in 1911 and became part of the range for 1912.
During the war Siddeley-Deasy made amubulances on their car chassis, and trucks under contract from Maudslay. In 1919 Sir W.G. Armstrong Whitworth & Co. bought Siddeley-Deasey for £419,750 to form the Armstrong-Whitworth Development Co. Armstrong-siddeley Motors was formed as a subsidiary, and a few months later the 30hp Armstrong-Siddeley car was launched.
Source: Nick Georgano / The Beaulieu Encyclopaedia of the Automobile