 | Bob Beacham |
 | Mary Game |
 | Tom Harmon |
Stewart MacPherson - The Twenty Questions Team Moderator | |
 | Jack Train - The Twenty Questions Team Member |
 | Jeanne De Casalis - The Twenty Questions Team Guest Artiste |
Daphne Padel - The Twenty Questions Team Member | |
Richard Dimbleby - The Twenty Questions Team Member | |
Norman Hackforth - The Twenty Questions Team 'Mystery Voice' | |
 | Detective Inspector Charlton |
 | Olive Tavey |
 | Police Commissioner |
 | Maurice Emery KC |
 | Police Officer 'Tiny' White |
 | John Grimshaw |
 | Record News Editor |
 | Echo News Editor |
 | General Maitland-Webb |
 | Mohammed Ali |
Stewart MacPherson's Secretary | |
 | Cheshire Cheese Waiter |
 | Doctor |
 | Commissionaire |
 | 2nd Plainclothesman |
 | 1st Newsboy |
 | Police Doctor |
 | Golf Club Barman |
 | Laundry Delivery Man |
 | Detective |
 | Crewman with Prompt Board |
 | 20 Questions Audience Member |
 | Mrs. Tavey's Neighbour |
 | McIntyre |
 | Frederick 'Ricky' Tavey |
 | Undetermined Secondary Role |