Colin Firth as Ewen Montagu

Matthew Macfadyen as Charles Cholmondeley

Kelly Macdonald as Jean Leslie

Penelope Wilton as Hester Leggett

Johnny Flynn as Ian Fleming

Jason Isaacs as Admiral John Godfrey

Mark Gatiss as Ivor Montazac

Hattie Morahan as Iris Montazac

Paul Ritter as Bentley Purchase

Simon Russell Beale as Winston Churchill

Lorne MacFadyen as Sgt. Roger Dearborn / Glyndwr Michael

Markus von Lingen as Adolf Clauss

Ruby Bentall as Connie Bukes

Alex Jennings as John Masterman

Ellie Haddington as Hilda Georgina Cholmondeley

Nicholas Rowe as Capt. David Ainsworth

Will Keen as Salvador Gomez-Beare

Mark Bonnar as Jock Horsfall

James Fleet as Charles Fraser-Smith

Alexander Beyer as Karl Kuhlenthal

Nico Birnbaum as Colonel Alexis von Roenne

Pep Tosar as Admiral Moreno

Alba Brunet as Ana Flores

Pedro Casablanc as Dr. Del Torno

Óscar Zafra as Colonel Cerruti

Javier Godino as Judge Pascual del Pobil

Jonjo O'Neill as Teddy

Amy Marston as Nurse Tate

Gabrielle Creevy as Doris Michael

Simon Rouse as Coroner Birtwistle

Paul Lancaster as Coroner Pinfield

Michael Bott as Frank Sawyer (Churchill Butler)

Charlotte Hamblin as Patricia Trehearne

Rufus Wright as Lt. Bill Jewell