Ioan Gruffudd as William Wilberforce

Romola Garai as Barbara Spooner

Benedict Cumberbatch as William Pitt

Albert Finney as John Newton

Michael Gambon as Lord Charles Fox

Rufus Sewell as Thomas Clarkson

Youssou N'Dour as Olaudah Equiano

Ciarán Hinds as Lord Tarleton

Toby Jones as Duke of Clarence

Nicholas Farrell as Henry Thornton

Sylvestra Le Touzel as Marianne Thornton

Jeremy Swift as Richard the Butler

Stephen Campbell Moore as James Stephen

Bill Paterson as Lord Dundas

Nicholas Day as Sir William Dolben

Georgie Glen as Hannah More

Nicholas Woodeson as Harrison

Tom Fisher as John Ramsay

Richard Ridings as Speaker of the House

David Hunt as Lord Camden

David Toole as Beggar

Alex Blake as Heckler

Angie Wallis as Marjorie

Harry Audley as Edward Hope (Quaker)

Chris Barnes as Michael Shaw (Quaker)

Tom Knight as Physician

Andrew Whipp as MP 1

Andrew Neil as MP 2

Estelle Morgan as Maid

Philip Dunbar as Camber

Adam Woodroffe as Parliamentary Clerk

Joseph Traynor as Newton's Secretary

Simon Delaney as Young Parliamentary Officer

Neville Phillips as Old Parliamentary Official

Eki Maria as Young African Woman

Daniel Naprous as Delivery Coach Driver

Peter White as Delivery Assistant