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.
The film was used as part of the RAF Initial Officer Training at RAF Cranwell (at least until the 1990s), as it deals with the conflict of man-management of others versus having to perform the task as well, whilst put in a setting that would be relevant to future officers.
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.
Some of the Hurricane fighters in the film were borrowed from the Portuguese government.
Director George More O'Ferrall drew on his own personal experiences for the film. He was a Royal Artillery staff officer at Fighter Command HQ during the Battle of Britain.