Patricia Neal

Susan North

Helmut Dantine

The Stranger

Derek Bond

Arthur Walker

Cyril Luckham

Dr. Meinard

Willoughby Gray

Tom Harding

Marigold Russell

Gretchen Harding

Arthur Young

Scientist

Kenneth Edwards

Charles Dixon

David Garth

First Police Officer

Stanley Van Beers

General

Nigel Green

Second Police Officer

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)