De Havilland Mosquito
More perhaps than any other single figure, Freeman was responsible for the RAF ordering the Hawker Hurricane, Supermarine Spitfire, De Havilland Mosquito, Avro Lancaster, Handley-Page Halifax and Hawker Tempest. He played an equally vital role in the development of the Merlin-engined P-51 Mustang, providing North American Aviation with the original specification and then installing Rolls-Royce Merlin engines in place of the unsatisfactory Allison V-1710 engines.