The film required a large number of period aircraft. In September 1965 producers Harry Saltzman and S. Benjamin Fisz contacted former RAF Bomber Command Group Captain T.G. 'Hamish' Mahaddie to find the aircraft and arrange their use. Eventually 100 aircraft were employed, called the "35th largest air force in the world". With Mahaddie's help, the producers located 109 Spitfires in the UK, of which 27 were available although only 12 could be made flyable. Mahaddie negotiated use of six Hawker Hurricanes, of which three were flying. The film helped preserve these aircraft, including a rare Spitfire Mk II which had been a gate guardian at RAF Colerne in Wiltshire.