John Dodsworth

as Clayton Palmer

as Calender

as Lt. Meyerdorf

as Dr. Bert Dilling

as Sir Edgar Whipsnade

as Dr. Carthwright

as Maj. MacStreet

as Compton - Cynthia's First Man (uncredited)

as Sir William Drayton

as Sergeant (uncredited)

as Baron de la Ma de la Toulon (uncredited)

as Favell

as Cyril

as Roy Lucas