Kenneth More
— William Blood
Shirley Anne Field
— Polly
Norman Bird
— Herbert
Michael Hordern
— Dr. Davidson
John Glyn-Jones
— Dr. Wilmot
Charles Gray
— Leo
Bernard Horsfall
— Rex
Bruce Boa
— Roy
Noel Purcell
— Prosecutor
Ed Devereaux
— Storekeeper
John Phillips
— Professor Stephens
Edward Burnham
— Test Chamber Scientist