 Jack HawkinsSupt Tom Halliday | Supt Tom Halliday |
 John StrattonSergeant Ward | Sergeant Ward |
 Dorothy AlisonMary Halliday | Mary Halliday |
| MMichael BrookeTony Halliday | Tony Halliday |
 Sam KyddPolice Constable in Information Room | Police Constable in Information Room |
 Glyn HoustonDetective Sergeant in 'Q' car | Detective Sergeant in 'Q' car |
 Richard LeechNightwatchman / Gilson | Nightwatchman / Gilson |
| NNewton BlickDeputy Commander | Deputy Commander |
 Geoffrey KeenChief Superintendent Jim Malcolm | Chief Superintendent Jim Malcolm |
 Sydney TaflerStone | Stone |
 Peter BurtonCreasey | Creasey |
 George RoseSlob | Slob |
 Arthur RigbyDetective Inspector at Chester | Detective Inspector at Chester |
 Ralph TrumanColonel Blenkinsop | Colonel Blenkinsop |
 Ian BannenThe Young Workman - Stanley James | The Young Workman - Stanley James |
 Maureen DavisThe Young Workman's Wife - Mrs. James | The Young Workman's Wife - Mrs. James |
| JJohn WarwickDetective Inspector at Shipping Office | Detective Inspector at Shipping Office |
 Joss AmblerCashier at Shipping Office | Cashier at Shipping Office |
 Barry KeeganDetective Constable in Hospital Ward | Detective Constable in Hospital Ward |
 Alec McCowenHouse Surgeon | House Surgeon |
 Harry LockeSecondhand Dealer | Secondhand Dealer |
 Nicholas ParsonsPolice Constable Bates | Police Constable Bates |
| WWarwick AshtonNewspaper Circulation Manager | Newspaper Circulation Manager |
| UUrsula HowellsMrs. Elliot / Mrs. Gilson | Mrs. Elliot / Mrs. Gilson |
 David DaviesWelsh Police Constable | Welsh Police Constable |
| JJulie MiltonWelsh Newsagent's Daughter | Welsh Newsagent's Daughter |
 Meredith EdwardsMr. Thomas | Mr. Thomas |
 Harold GoodwinOfficial at Somerset House | Official at Somerset House |
 John WelshHouse Agent at Shepperton | House Agent at Shepperton |
| GGillian WebbHousewife at Shepperton | Housewife at Shepperton |
