 Keira KnightleyGeorgiana Cavendish, Duchess of Devonshire | Georgiana Cavendish, Duchess of Devonshire |
 Ralph FiennesDuke of Devonshire | Duke of Devonshire |
 Charlotte RamplingLady Spencer | Lady Spencer |
 Dominic CooperCharles Grey | Charles Grey |
 Hayley AtwellBess Foster | Bess Foster |
 Simon McBurneyCharles Fox | Charles Fox |
 Aidan McArdleRichard Brinsley Sheridan | Richard Brinsley Sheridan |
 John ShrapnelGeneral Grey | General Grey |
 Alistair PetrieHeaton | Heaton |
 Patrick GodfreyDr. Neville | Dr. Neville |
 Michael MedwinSpeechmaker | Speechmaker |
 Justin EdwardsMacaroni | Macaroni |
 Richard McCabeSir James Hare | Sir James Hare |
 Calvin A. DeanDevonshire House Servant (as Calvin Dean) | Devonshire House Servant (as Calvin Dean) |
 Hannah StokelyDevonshire House Maid | Devonshire House Maid |
| AAndrew ArmourBurleigh | Burleigh |
| EEmily JewellNanny | Nanny |
 Bruce MackinnonSir Peter Teazle | Sir Peter Teazle |
 Georgia KingLady Teazle | Lady Teazle |
 Luke NorrisFootman | Footman |
| EEva HrelaCharlotte (Age 3) | Charlotte (Age 3) |
| PPoppy WigglesworthCharlotte (Age 9) | Charlotte (Age 9) |
| EEmily CohenHarryo | Harryo |
| MMercy Fiennes TiffinLittle G | Little G |
| SSebastian ApplewhiteAugustus | Augustus |
| AAngus McEwanLord Robert | Lord Robert |
 Kate BurdetteLady Harriet | Lady Harriet |
 Laura StevelyLady Elizabeth | Lady Elizabeth |
 Benjamin NobleLord Ambrose (as Ben Garlick) | Lord Ambrose (as Ben Garlick) |
 Max BennettLord Walter | Lord Walter |
