 | Dennis Price als Louis Mazzini / His Father |
 | Alec Guinness als The D'Ascoyne Family: The Duke / The Banker / The Parson / The General / The Admiral / Young Ascoyne / Young Henry / Lady Agatha |
 | Joan Greenwood als Sibella |
 | Valerie Hobson als Edith D'Ascoyne |
 | Audrey Fildes als Mama |
 | Miles Malleson als The Hangman |
 | Clive Morton als The Prison Governor |
 | John Penrose als Lionel Holland |
 | Cecil Ramage als Crown Counsel |
 | Hugh Griffith als Lord High Steward |
 | John Salew als Mr. Perkins |
 | Eric Messiter als Inspector Burgoyne |
| Lyn Evans als The Farmer |
| Barbara Leake als The Schoolmistress |
| Peggy Ann Clifford als Maud Redpole |
| Anne Valery als The Girl in the Punt |
 | Arthur Lowe als The Reporter |
 | Peter Gawthorne als First Lord Delivering Verdict (uncredited) |
| Molly Hamley-Clifford als Lady Redpole (uncredited) |
| Leslie Handford als Gamekeeper Hoskins (uncredited) |
| Cavan Malone als Young Graham (uncredited) |
 | Jeremy Spenser als Young Louis (uncredited) |
 | Carol White als Young Sibella (uncredited) |
 | Laurence Naismith als Warder in Jail (uncredited) |
| Gordon Phillott als Clerk of Parliament (uncredited) |
 | Richard Wattis als Defence Counsel (uncredited) |
| Harold Young als Captain (uncredited) |
| Robert Hamer | Director |
| Peter Tanner | Editor |
| John Dighton | Screenplay |
| Michael Balcon | Producer |
| Robert Hamer | Screenplay |
| Douglas Slocombe | Director of Photography |
| Roy Horniman | Novel |
| Ernest Irving | Original Music Composer |
| Nancy Mitford | Screenplay |
| Harry Frampton | Makeup Artist |
| Pearl Orton | Hairstylist |
| Ernest Taylor | Makeup Artist |
| John Jympson | Assistant Editor |
| Leigh Aman | Unit Production Manager |
| Roy Baker | Assistant Editor |
| Barbara Barnard | Hairstylist |
| Daphne Martin | Hairstylist |
| Hal Mason | Production Supervisor |
| Norman Priggen | Assistant Director |
| Sydney Pearson | Special Effects |
| William Kellner | Art Direction |
| Seth Holt | Editorial Services |
| Michael Relph | Associate Producer |
| Anthony Mendleson | Costume Design |
| Bert Davey | Assistant Art Director |
| Jeff Seaholme | Camera Operator |
| Geoffrey Dickinson | Special Effects |
| Stephen Dalby | Sound Director |
| Ernest Irving | Conductor |
| Phyllis Crocker | Continuity |
| Wolfgang Amadeus Mozart | Music |
| John W. Mitchell | Sound Recordist |
| Philharmonia Orchestra | Music |
