Armstrong Siddeley was a British engineering group that operated during the first half of the 20th century. It was formed in 1919 and is best known for the production of luxury vehicles and aircraft engines.

The Bristol Aeroplane Company, originally the British and Colonial Aeroplane Company, was both one of the first and one of the most important British aviation companies, designing and manufacturing both airframes and aircraft engines. Notable aircraft produced by the company include the 'Boxkite', the Bristol Fighter, the Bulldog, the Blenheim, the Beaufighter, and the Britannia, and much of the preliminary work which led to Concorde was carried out by the company. In 1956 its major operations were split into Bristol Aircraft and Bristol Aero Engines. In 1959, Bristol Aircraft merged with several major British aircraft companies to form the British Aircraft Corporation (BAC) and Bristol Aero Engines merged with Armstrong Siddeley to form Bristol Siddeley.