Leslie Howard as R.J. Mitchell

David Niven as Geoffrey Crisp

Rosamund John as Diana Mitchell

Roland Culver as Commander Bride

Anne Firth as Miss Harper

David Horne as Mr. Higgins

J.H. Roberts as Sir Robert McLean

Derrick De Marney as Squadron Leader Jefferson

Rosalyn Boulter as Mabel Lovesay

Herbert Cameron as MacPherson

Toni Edgar-Bruce as Lady Houston

Gordon McLeod as Major Buchan

George Skillan as Mr. Royce

Erik Freund as Messerschmitt

Fritz Wendhausen as Von Straben

John Chandos as Krantz

Victor Beaumont as Von Crantz

Suzanne Clair as Madeleine

Filippo Del Giudice as Bertorelli

Brefni O'Rorke as The Specialist

Gerry Wilmot as Radio Announcer

Jack Peach as Radio Announcer