The Bristol Orion aero engine is a two-shaft turboprop intended for use in later marks of the Bristol Britannia and the Canadair CL-44. Although the engine was built and underwent a development program, the BE.25 Orion project was cancelled in 1958 by the British Ministry of Supply in favour of the Rolls-Royce Tyne. In addition, interest in turboprop-powered aircraft was beginning to wane, because of the successful introduction of the Boeing 707 and Douglas DC-8 jetliners into airline service.

The Bristol Type 175 Britannia is a retired British medium-to-long-range airliner built by the Bristol Aeroplane Company in 1952 to meet British civilian aviation needs. During development two prototypes were lost and the turboprop engines proved susceptible to inlet icing, which delayed entry into service while solutions were sought.