 | Benedict Cumberbatch | .... | Alan Turing |
 | Keira Knightley | .... | Joan Clarke |
 | Matthew Goode | .... | Hugh Alexander |
 | Rory Kinnear | .... | Detective Robert Nock |
 | Allen Leech | .... | John Cairncross |
 | Matthew Beard | .... | Peter Hilton |
 | Charles Dance | .... | Commander Denniston |
 | Mark Strong | .... | Stewart Menzies |
 | James Northcote | .... | Jack Good |
 | Tom Goodman Hill | .... | Sergeant Staehl |
 | Steven Waddington | .... | Superintendent Smith |
 | Ilan Goodman | .... | Keith Furman |
 | Jack Tarlton | .... | Charles Richards |
 | Alex Lawther | .... | Young Alan Turing |
 | Jack Bannon | .... | Christopher Morcom |
 | Tuppence Middleton | .... | Helen |
 | Dominic Charman | .... | Sherborne Student 1 |
 | James G Nunn | .... | Sherborne Student 2 |
 | Charlie Manton | .... | Sherborne Student 3 |
 | David Charkham | .... | Joan's Father |
 | Victoria Wicks | .... | Joan's Mother |
 | Andrew Havill | .... | Teacher |
 | Laurence Kennedy | .... | Headmaster |
 | Tim Van Eyken | .... | MI6 Agent |
 | Will Bowden | .... | Military Policeman |
 | Miranda Bell | .... | Margaret |
 | Tim Steed | .... | Electrical Assistant |
 | Lee Asquith-Coe | .... | MI6 Agent (uncredited) |
 | Hayley Joanne Bacon | .... | Woman in Crowd (uncredited) |
 | Lauren Beacham | .... | RAF Wren (uncredited) |
 | Ingrid Benussi | .... | Dancer (uncredited) |
 | Nicholas Blatt | .... | Ministry Man (uncredited) |
 | Carmen Coupeau Borras | .... | Detective Robert Nock's Secretary (uncredited) |
 | Jack Brash | .... | Evacuee (uncredited) |
 | Ancuta Breaban | .... | Wren (uncredited) |
 | Heather Broderick | .... | Passerby (uncredited) |
 | Peter Brown | .... | Navy Captain (uncredited) |
 | Alex Corbet Burcher | .... | Dancer (uncredited) |
 | Grace Calder | .... | Assistant Wren (uncredited) |
 | Richard Campbell | .... | Crossword Man in Pub (uncredited) |
 | Daniel Chapple | .... | MI6 Agent (uncredited) |
 | Winston Churchill | .... | Himself(archive footage) (uncredited) |
 | Lisa Colquhoun | .... | Joan Clarke's Friend (uncredited) |
 | Alexander Cooper | .... | Bletchley Park Agent (uncredited) |
 | Chris Cowlin | .... | Military Police Officer (uncredited) |
 | Kirsty-Marie Day | .... | WRAF Officer (uncredited) |
 | Leigh Dent | .... | Passerby (uncredited) |
 | Esther Eden | .... | WW2 Wren (uncredited) |
 | Sam Exley | .... | Military Policeman 3 (uncredited) |
 | Ben Farrow | .... | Military Police (uncredited) |
 | Mike Firth | .... | Crossword Enthusiast (uncredited) |
 | Hannah Flynn | .... | Wren (uncredited) |
 | Guna Gultniece | .... | Passerby (uncredited) |
 | Adolf Hitler | .... | Himself(archive footage) (uncredited) |
 | Leigh Holland | .... | M16 Agent (uncredited) |
 | Luke Hope | .... | MI6 Exam Agent (uncredited) |
 | Vera Horton | .... | Nunn (uncredited) |
 | Ashley Hudson | .... | British soldier (uncredited) |
 | Michael John-Lewis | .... | Lieutenant (uncredited) |
 | Denis Khoroshko | .... | Civilian (uncredited) |
 | Debra Leigh-Taylor | .... | Evacuee (uncredited) |
 | Stuart Matthews | .... | Bletchley Park Operative (uncredited) |
 | Amber-Rose May | .... | Joan Clarke's Friend (uncredited) |
 | Arnold Montey | .... | M16 Agent (uncredited) |
 | Samantha Moran | .... | Wren (uncredited) |
 | Gina Morrish | .... | Evacuee (uncredited) |
 | Adam Nowell | .... | Technician (uncredited) |
 | Joseph Oliveira | .... | M16 Agent (uncredited) |
 | Ryan Parker | .... | Young Guy on the Street (uncredited) |
 | John Redman | .... | Young Officer (uncredited) |
 | Julio Romeo | .... | Police officer (uncredited) |
 | Adam Scown | .... | Crossword Soldier (uncredited) |
 | Scott Stevenson | .... | Bletchley (uncredited) |
 | Harry S. Truman | .... | Himself(archive footage) (uncredited) |
 | Emilia Ufir | .... | Secretary (uncredited) |
 | Mark Underwood | .... | Crossword Man (uncredited) |
 | Nicola-Jayne Wells | .... | First Aid Nurse (uncredited) |
 | Josh Wichard | .... | German Spy Plane Pilot (uncredited) |