Professor Marcus

Alec Guinness

Acting

Claude, alias 'Major Courtney'

Cecil Parker

Acting

Louis, alias 'Mr. Harvey'

Herbert Lom

Acting

Harry, alias 'Mr. Robinson'

Peter Sellers

Acting

'One-Round', alias 'Mr. Lawson'

Danny Green

Acting

Mrs. Wilberforce

Katie Johnson

Acting

The Superintendent

Jack Warner

Acting

The Sergeant

Philip Stainton

Acting

The Barrow Boy

Frankie Howerd

Acting

Large Lady (uncredited)

Madge Brindley

Acting

Hypatia (uncredited)

Hélène Burls

Acting

Cab Driver (uncredited)

Kenneth Connor

Acting

Burglar (uncredited)

Michael Corcoran

Acting

Parcels Clerk (uncredited)

Harold Goodwin

Acting

Junk Man (uncredited)

Fred Griffiths

Acting

Miss Pringle (uncredited)

Lucy Griffiths

Acting

Security Van Driver (uncredited)

George Hilsdon

Acting

Station Master (uncredited)

Vincent Holman

Acting

Security Guard (uncredited)

Stratford Johns

Acting

Second Cab Driver (uncredited)

Sam Kydd

Acting

Lettice (uncredited)

Edie Martin

Acting

Detective (uncredited)

Jack Melford

Acting

(uncredited)

Arthur Mullard

Acting

Constable (uncredited)

Ewan Roberts

Acting

Radio Car Policeman (uncredited)

George Roderick

Acting

Nervous Man (uncredited)

John Rudling

Acting

Pavement Artist (uncredited)

Leonard Sharp

Acting

Detective at Parcels Office (uncredited)

Peter Williams

Acting

Policeman (uncredited)

Neil Wilson

Acting

Constance (uncredited)

Phoebe Hodgson

Acting