Joan Hickson was booked for a featured role but dropped out.
Ronald Adam plays the part of a Group Controller. During the Battle of Britain, he was Squadron Leader Ronald Adam and was the Group Controller at Hornchurch.
Some of the Hurricane fighters in the film were borrowed from the Portuguese government.
The word "angels" in the title was Second World War RAF slang for altitude: "angels one five" refers to an altitude of 15,000 feet.