Characters played by Patricia Neal
Susan North
Characters played by Helmut Dantine
The Stranger
Characters played by Derek Bond
Arthur Walker
Characters played by Cyril Luckham
Dr. Meinard
Characters played by Willoughby Gray
Tom
Characters played by Marigold Russell
Gretchen
Characters played by Arthur Young
Scientist
Characters played by Kenneth Edwards
Charles Dixon
Characters played by David Garth
First Police Officer
Characters played by Stanley Van Beers
General
Characters played by Nigel Green
Second Police Officer
Characters played by Graham Stuart
Police Chief
Characters played by Jack Gwillim
Representative of Parliament
Characters played by John Le Mesurier
Man at Desk
Characters played by Peter Sallis
Soldier