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

Basil Dearden