 Dennis PriceLouis Mazzini / His Father | Louis Mazzini / His Father |
 Alec GuinnessThe D'Ascoyne Family: The Duke / The Banker / The Parson / The General / The Admiral / Young Ascoyne / Young Henry / Lady Agatha | The D'Ascoyne Family: The Duke / The Banker / The Parson / The General / The Admiral / Young Ascoyne / Young Henry / Lady Agatha |
 Joan GreenwoodSibella | Sibella |
 Valerie HobsonEdith D'Ascoyne | Edith D'Ascoyne |
 Audrey FildesMama | Mama |
 Miles MallesonThe Hangman | The Hangman |
 Clive MortonThe Prison Governor | The Prison Governor |
 John PenroseLionel Holland | Lionel Holland |
 Cecil RamageCrown Counsel | Crown Counsel |
 Hugh GriffithLord High Steward | Lord High Steward |
 John SalewMr. Perkins | Mr. Perkins |
| EEric MessiterInspector Burgoyne | Inspector Burgoyne |
| LLyn EvansThe Farmer | The Farmer |
| BBarbara LeakeThe Schoolmistress | The Schoolmistress |
| PPeggy Ann CliffordMaud Redpole | Maud Redpole |
| AAnne ValeryThe Girl in the Punt | The Girl in the Punt |
 Arthur LoweThe Reporter | The Reporter |
 Peter GawthorneFirst Lord Delivering Verdict (uncredited) | First Lord Delivering Verdict (uncredited) |
| MMolly Hamley-CliffordLady Redpole (uncredited) | Lady Redpole (uncredited) |
| LLeslie HandfordGamekeeper Hoskins (uncredited) | Gamekeeper Hoskins (uncredited) |
| CCavan MaloneYoung Graham (uncredited) | Young Graham (uncredited) |
 Jeremy SpenserYoung Louis (uncredited) | Young Louis (uncredited) |
 Carol WhiteYoung Sibella (uncredited) | Young Sibella (uncredited) |
 Laurence NaismithWarder in Jail (uncredited) | Warder in Jail (uncredited) |
| GGordon PhillottClerk of Parliament (uncredited) | Clerk of Parliament (uncredited) |
 Richard WattisDefence Counsel (uncredited) | Defence Counsel (uncredited) |
| HHarold YoungCaptain (uncredited) | Captain (uncredited) |
| SStanley BeardWarder (uncredited) | Warder (uncredited) |
| NNorman FisherMember of D'Ascoyne Household (uncredited) | Member of D'Ascoyne Household (uncredited) |
| MMaxwell FosterWarder (uncredited) | Warder (uncredited) |
