Patricia Neal
Susan North
Helmut Dantine
The Stranger
Derek Bond
Arthur Walker
Cyril Luckham
Dr. Meinard
Willoughby Gray
Tom Harding
M
Marigold Russell
Gretchen Harding
Arthur Young
Scientist
Kenneth Edwards
Charles Dixon
D
David Garth
First Police Officer
Stanley Van Beers
General
Nigel Green
Second Police Officer
G
Graham Stuart
Police Chief
Jack Gwillim
Representative of Parliament (uncredited)
John Le Mesurier
Official/Man at Desk (uncredited)
Hugh Moxey
Secretary of the Interior (uncredited)
Peter Sallis
Soldier (uncredited)