George Cole

George Archibald Potts

Oskar Homolka

Zekov

Nadia Gray

Tania

Wilfrid Hyde-White

Sir Hubert Wells

Richard Wattis

Barnes

Irene Handl

Mrs. Tidmarsh

Christopher Lee

Russian Agent (uncredited)

Frederick Leister

Prime Minister

Frederick Valk

Rakov

Geoffrey Sumner

Pike

Ronald Adam

Barworth Controller

Edwin Styles

Barworth Superintendent

Kynaston Reeves

Barworth Director

Ernest Jay

Professor Layton

Michael Medwin

Smedley

Mario Zampi