Bristol-Siddeley Engines Limited was created from the merger of Bristol Aero Engines and Armstrong Siddeley Motors in 1958, and was based in Bristol, Filton and Coventry.

By 1961 the company was designing and manufacturing aircraft piston engines, gas turbine engines, and propeller turbine engines; industrial and marine turbine engines; industrial, marine and rail traction diesel engines; cars; gas bearing compressors; beaver ball screws, ball ways and ball splines, and other engineering products. The business had 25,000 employees and was listed as a subsidiary of the Bristol Aeroplane Company and the Hawker Siddeley Group. In the same year it acquired de Havilland Engines and Blackburn Engines.

In 1966 Bristol-Siddeley was acquired by Rolls-Royce.