Armstrong-Siddeley was a British company operating during the first half of the 20th century. It had two aspects motor cars, Armstrong Siddeley Motors Ltd, and aero-engines and aircraft, via the Sir W G Armstrong Whitworth Company, as a result of the merger of the interests of two Coventry-based companies, Armstrong-Whitworth and Siddeley-Deasy in 1919.
A predecessor company, Siddeley Autocars of Coventry, was founded by John Davenport Siddeley (1866-1953) in 1902. Its products were heavily based on Peugeots using many of their parts but fitted with English bodies. This company merged with Wolseley in 1905 and made stately Wolseley-Siddeley motorcars. They were used by Queen Alexandra and the Duke of York, the later King Edward VII.
In 1909 J.D. Siddeley resigned from Wolseley and took over the Deasy Motor Co and the company became known as Siddeley-Deasy. In 1912 the cars used the slogan "As silent as the sphinx" and started to sport a Sphinx as a bonnet ornament.