Barry Jones
— Professor John Malcolm Francis Willingdon
André Morell
— Superintendent G.W. Folland
Olive Sloane
— Goldie Phillips
Sheila Manahan
— Ann Willingdon
Hugh Cross
— Stephen Lane
Joan Hickson
— Mrs. Emily Georgina Peckett
Ronald Adam
— Arthur Lytton, the Prime Minister
Marie Ney
— Mrs. Willingdon
Joss Ackland
— Station Policeman
Marianne Stone
— Woman in Phone Box
John Stratton
— Army Mechanic
George Spence
— Man on Bus (uncredited)