Rebecca Hall as Florence Cathcart

Dominic West as Robert Mallory

Imelda Staunton as Maud Hill

Isaac Hempstead Wright as Tom

Lucy Cohu as Constance Strickland

Cal MacAninch as Freddie Strickland

John Shrapnel as Reverend Hugh Purslow

Diana Kent as Harriet Cathcart

Richard Durden as Alexander Cathcart

Alfie Field as Victor Parry

Tilly Vosburgh as Vera Flood

Ian Hanmore as Albert Flood

Andrew Havill as George Vandermeer

Anastasia Hille as Dorothy Vandermeer

Joseph Mawle as Edward Judd

Shaun Dooley as Malcolm McNair

Steven Cree as Sergeant Evans

Felix Soper as Julian Dowden

Sidney Johnston as John Franklin

Spike White as Alistair Howell

Charlie Callaghan as Chris Hartley

James Kirkham as William Ramsbottom

Ewan Andrew Walker as Richard McGorian

Adam Thomas Wright as Max Tebbitts

Ben Greaves-Neal as Child Impostor

Daniel Pirrie as Captain Mills

Nicholas Amer as Edgar Hirsthwit

Nick Murphy as Teacher 1

Neil Broome as School Master (uncredited)