Alec Guinness
Professor Marcus
Cecil Parker
Claude, alias 'Major Courtney'
Herbert Lom
Louis, alias 'Mr. Harvey'
Peter Sellers
Harry, alias 'Mr. Robinson'
Danny Green
'One-Round', alias 'Mr. Lawson'
Katie Johnson
Mrs. Wilberforce
Jack Warner
The Superintendent
Philip Stainton
The Sergeant
Frankie Howerd
The Barrow Boy
Madge Brindley
Large Lady (uncredited)
Hélène Burls
Hypatia (uncredited)
Kenneth Connor
Cab Driver (uncredited)
Michael Corcoran
Burglar (uncredited)
Harold Goodwin
Parcels Clerk (uncredited)
