Bristol Siddeley was a British aerospace company formed in 1956 through the merger of Bristol Aeroplane Company and Siddeley Aircraft Company. The company specialized in the design and manufacture of aircraft engines, contributing significantly to both military and civilian aviation. In 1966, Bristol Siddeley became part of Rolls-Royce, further enhancing its capabilities in engine technology. The company was known for producing notable engines, including the Orpheus and Aero-Engine, which powered various aircraft, including the Hawker Siddeley Buccaneer and Vickers VC10.