Will Hay as William Potts / Muller

Frank Pettingell as Professor Hoffman

Julien Mitchell as General Von Glotz

Charles Hawtrey as Max

Barry Morse as Kurt

Peter Ustinov as Krauss

Peter Croft as Hans

Anne Firth as Lena

Leslie Harcourt as Vogel

Jeremy Hawk as A.D.C.

Raymond Lovell as Schmidt

Aubrey Mallalieu as Rector

John Williams as Maj. Bishop

Lawrence O'Madden as Col. Truscott

John Boxer as British Pilot

Clifford Buckton as MI5 Man (uncredited)

Arthur Denton as Detective Carter (uncredited)

Leslie Dwyer as German Soldier on Train

Richard George as German Pilot

Walter Gotell as SS Guard

William Hartnell as German Officer at Station

Bryan Herbert as Airport Official

Vincent Holman as Member of the General Staff

Charles Paton as Passenger Arrested on Train

Lloyd Pearson as Train Passenger

Johnnie Schofield as 1st Observer (uncredited)

Harry Terry as SS Guard (uncredited)

Jack Vyvyan as Detective Evans (uncredited)

H Victor Weske as SS Officer on Train (uncredited)