 | Bernard Lee | ... | Supt. Meredith / ... (5 episodes, 1960-1964) |
| Bernard Archard | ... | Insp. Trainer / ... (4 episodes, 1961-1964) |
| Allan Cuthbertson | ... | Det. Supt. Cowley / ... (4 episodes, 1960-1965) |
| John Carson | ... | Insp. Jackson / ... (4 episodes, 1962-1964) |
| Alfred Burke | ... | Davison / ... (4 episodes, 1961-1963) |
| Marianne Stone | ... | Alice Preston / ... (4 episodes, 1963-1965) |
| Norma Parnell | ... | Day Nurse (4 episodes, 1960-1963) |
| Stanley Morgan | ... | Sgt. Anson / ... (4 episodes, 1960-1962) |
| Tony Wall | ... | Constable Huntly / ... (4 episodes, 1961-1965) |
| Maxine Audley | ... | Liz Teasdale / ... (3 episodes, 1961-1964) |
| Jacqueline Ellis | ... | Elsa Marlowe / ... (3 episodes, 1961-1963) |
| Paul Daneman | ... | Frank Griffiths / ... (3 episodes, 1961-1962) |
| Nadja Regin | ... | Mrs. Reynolds / ... (3 episodes, 1962-1964) |
| Moira Redmond | ... | Diana Marsh / ... (3 episodes, 1960-1962) |
| Michael Coles | ... | Frank Murray / ... (3 episodes, 1961-1964) |
| Anthony Newlands | ... | Leo Hagen / ... (3 episodes, 1961-1963) |
| Jennifer Daniel | ... | Barbara Blair / ... (3 episodes, 1960-1963) |
| Derek Francis | ... | Arthur Tilsley / ... (3 episodes, 1961-1964) |
| Victor Platt | ... | Harold Strickland / ... (3 episodes, 1961-1962) |
| John Glyn-Jones | ... | Dr. Maurice Tarn / ... (3 episodes, 1961-1964) |
| Philip Locke | ... | David Hughes / ... (3 episodes, 1963-1964) |
| Richard Warner | ... | Crabtree / ... (3 episodes, 1961-1963) |
| William Abney | ... | James Tynewood / ... (3 episodes, 1960-1964) |
| Richard Vernon | ... | John Crewe / ... (3 episodes, 1960-1963) |
| Jack Watson | ... | Insp. Bolam / ... (3 episodes, 1960-1963) |
| Clifford Earl | ... | Detective Sergeant Wentworth / ... (3 episodes, 1961-1963) |
| Brian Haines | ... | Felix Carstairs / ... (3 episodes, 1963-1964) |
| Denis Holmes | ... | Fraser / ... (3 episodes, 1961-1964) |
| John Miller | ... | Lord Clandon / ... (3 episodes, 1963-1964) |
| André Mikhelson | ... | Head Waiter (3 episodes, 1960-1962) |
| Peter Thomas | | (3 episodes, 1961-1964) |
| Jack Watling | ... | Frank Leamington / ... (3 episodes, 1961-1964) |
| Derrick Sherwin | ... | Alan / ... (3 episodes, 1961-1963) |
| Alec Bregonzi | ... | Cast member / ... (3 episodes, 1963-1964) |
| Anthony Bailey | ... | Charles - the Chauffeur (3 episodes, 1963-1964) |
| Victor Charrington | ... | Barman (3 episodes, 1962-1964) |
