Ed Stoppard
Alan Turing
Henry Goodman
Franz Greenbaum
Paul McGann
Himself - Narrator (voice)
Asa Briggs
Himself - Codebreaker, Bletchley Park
Jean Valentine
Herself - WRNS and Bombe Operator, Bletchley Park
David Leavitt
Himself - Alan Turing's Biographer
Rolf Noskwith
Himself - Codebreaker, Bletchley Park
Dermot Turing
Himself - Alan Turing's Nephew
Christopher Morcom
Himself - Christopher Morcom's Nephew (as Christopher Morcom QC)
Ian Stewart
Himself - University of Warwick (as Professor Ian Stewart)