David Oyelowo as Seretse Khama

Rosamund Pike as Ruth Williams-Khama

Tom Felton as Rufus Lancaster

Jack Davenport as Sir Alistair Canning

Terry Pheto as Naledi Khama

Laura Carmichael as Muriel Williams

Jessica Oyelowo as Lady Lilly Canning

Vusi Kunene as Tshekedi Khama

Nicholas Lyndhurst as George Williams

Arnold Oceng as Charles

Anastasia Hille as Dot Williams

Charlotte Hope as Olivia Lancaster

Theo Landey as Nash

Abena Ayivor as Ella Khama

Jack Lowden as Tony Benn

Zackary Momoh as Oluwu

Nicholas Rowe as Fenner Brockway

Billy Boyle as Reverend James Manners

Conny Stadler as Missionary

Kevin Hand as Manager

Ray Burnet as Reverend Leonard Patterson

Anton Lesser as Prime Minister Attlee

Michael Howe as Terence Bernard

Donald Molosi as Kabelo

Julian Firth as Mr. Speaker

Duncan Wisbey as Commonwealth Under-Secretary

Rupert Vansittart as Sir Ian Fraser

James Northcote as Roberts

Merveille Lukeba as Joe Appiah

Femi Ogunbanjo as Man from Rhodesia

Paul Putner as Porter

Will Featherstone as Reporter

Danny Babington as Reporter

Dave Perry as Idiot

Craig Whittaker as Idiot

Dean Roberts as Idiot

Kitty Devlin as Celia

Karl Farrer as Reporter (uncredited)