Bernard Lee

as Henry Houghton

William Sylvester

as Gordon Lonsdale

Margaret Tyzack

as Elizabeth Gee

David Kossoff

as Peter Kroger

Nancy Nevinson

as Helen Kroger

Thorley Walters

as Cmdr. Winters

Gillian Lewis

as Marjorie Shaw

Newton Blick

as P.O. Meadows

Philip Latham

as Captain Ray

Cyril Chamberlain

as Anderson

Justine Lord

as Christina

Patrick Barr

as Captain Warner

Derek Francis

as Chief Supt. Croft

Hector Ross

as Supt. Woods

Paul Eddington

as Johnnie (uncredited)

Richard Marner

as Colonel Monat (uncredited)

Geoffrey Palmer

as Police Officer (uncredited)

Bryan Pringle

as Surveillance Man (uncredited)

Andre Mikhelson

as Russian Embassy Official (uncredited)

Garry Marsh

as First Member at Lords (uncredited)

Basil Dignam

as Second Member at Lords (uncredited)

Brian Nissen

as Portland Official (uncredited)

Edwin Apps

as Blake (uncredited)

Fred Griffiths

as News Vendor (uncredited)

Anita West

as Tilly (uncredited)