| Name | Character | Episodes |
|---|---|---|
| Robert Ayres | Walter Allen | 43 |
| John Ireland | John Hunter | 36 |
| Ann Hanslip | Walter Allen's Secretary | 4 |
| Reginald Marsh | Inspector Martin | 2 |
| Robert Cawdron | Saxon | 1 |
| Ballard Berkeley | Harry Tyler | 1 |
| Ballard Berkeley | Jefford | 1 |
| Ballard Berkeley | Mansion | 1 |
| Frank Thornton | Long | 1 |
| Anton Rodgers | Barman | 1 |
| Valentine Dyall | Inspector Kellogg | 1 |
| Margaretta Scott | Mrs. Osborne | 1 |
| Robert Raglan | The Captain | 1 |
| Barrie Ingham | Petrie | 1 |
| Michael Balfour | Harry | 1 |
| Michael Balfour | Freddy | 1 |
| Ann Hanslip | Betty Fuller | 1 |
| Philip Latham | Cooke | 1 |
| Graham Ashley | Det. Sgt. Jameson | 1 |
| Richard Shaw | Henchman (uncredited) | 1 |