- B C
Benedict CumberbatchAlan Turing
- K K
Keira KnightleyJoan Clarke
- M G
Matthew GoodeHugh Alexander
- R K
Rory KinnearDetective Robert Nock
- A L
Allen LeechJohn Cairncross
- M B
Matthew BeardPeter Hilton
- C D
Charles DanceCommander Denniston
- M S
Mark StrongStewart Menzies
- J N
James NorthcoteJack Good
- T G
Tom Goodman-HillSergeant Staehl
- S W
Steven WaddingtonSuperintendent Smith
- I G
Ilan GoodmanKeith Furman
- J T
Jack TarltonCharles Richards
- A L
Alex LawtherYoung Alan Turing
- J B
Jack BannonChristopher Morcom
- T M
Tuppence MiddletonHelen
- D C
Dominic CharmanSherborne Student 1
- J G
James G. NunnSherborne Student 2
- C M
Charlie MantonSherborne Student 3
- D C
David CharkhamJoan's Father
- V W
Victoria WicksJoan's Mother
- A H
Andrew HavillTeacher
- L K
Laurence KennedyHeadmaster
- T v
Tim van EykenMI6 Agent
- W B
Will BowdenMilitary Policeman
- M B
Miranda BellMargaret
- T S
Tim SteedElectrical Assistant
- H J
Hayley Joanne BaconWoman in Crowd (uncredited)
- N B
Nicholas BlattMinistry Man (uncredited)
- A B
Ancuta BreabanWren (uncredited)
- A C
Alex Corbet BurcherDancer (uncredited)
- G C
Grace CalderAssistant Wren (uncredited)
- R C
Richard CampbellCrossword Man in Pub (uncredited)
- D C
Daniel ChappleMI6 Agent (uncredited)
- L C
Lisa ColquhounJoan Clarke's Friend (uncredited)
- A C
Alexander CooperBletchley Park Agent (uncredited)
- L D
Leigh DentPasserby (uncredited)
- S E
Sam ExleyMilitary Policeman 3 (uncredited)
- D G
Dennis GoodCivilian (uncredited)
- D L
Debra Leigh-TaylorEvacuee (uncredited)
- S M
Stuart MatthewsBletchley Park Operative (uncredited)
- J O
Joseph OliveiraMI6 Agent (uncredited)
- D G
David G. RobinsonPolice Sergeant White (uncredited)
- M U
Mark UnderwoodCrossword Man (uncredited)
- N W
Nicola-Jayne WellsFirst Aid Nurse (uncredited)
- J W
Joshua WichardGerman Spy Plane Pilot (uncredited)
