| Dennis Price | Louis Mazzini |
| Valerie Hobson | Edith D'Ascoyne |
| Joan Greenwood | Sibella Holland |
| Alec Guinness | The Duke / The Banker / The Parson / The General / The Admiral / Young Ascoyne / Young Henry / Lady Agatha |
| Audrey Fildes | Mama Mazzini |
| Miles Malleson | Mr. Elliott - the Hangman |
| Clive Morton | The Prison Governor Colonel |
| John Penrose | Lionel Holland |
| Cecil Ramage | Crown Counsel |
| Hugh Griffith | Lord High Steward |
| John Salew | Mr. Perkins |
| Eric Messiter | Inspector Burgoyne |
| Lyn Evans | The Farmer |
| Barbara Leake | Miss Waterman - the Schoolmistress |
| Peggy Ann Clifford | Maud Redpole |
| Anne Valery | Clothilde - the Girl in the Punt |
| Arthur Lowe | The Titbits Reporter |
| Stanley Beard | Warder (uncredited) |
| Maxwell Foster | Warder (uncredited) |
| Peter Gawthorne | First Lord Delivering Verdict (uncredited) |
| Molly Hamley-Clifford | Lady Redpole (uncredited) |
| Leslie Handford | Gamekeeper Hoskins (uncredited) |
| Nicholas Hill | Sergeant-at-Arms (uncredited) |
| Fletcher Lightfoot | Peer of the Realm (uncredited) |
| Cavan Malone | Young Graham (uncredited) |
| Laurence Naismith | Warder in Jail (uncredited) |
| Gordon Phillott | Clerk of Parliament (uncredited) |
| Jeremy Spenser | Young Louis (uncredited) |
| Ivan Staff | Valuer (uncredited) |
| Richard Wattis | Defence Counsel (uncredited) |
| Carol White | Young Sibella (uncredited) |
| Harold Young | Captain (uncredited) |
