Alan Turing
Joan Clarke
Hugh Alexander
Detective Robert Nock
John Cairncross
Peter Hilton
Commander Denniston
Stewart Menzies
Jack Good
Sergeant Staehl
Superintendent Smith
Keith Furman
Charles Richards
Young Alan Turing
Christopher Morcom
Helen
Sherborne Student 1
Sherborne Student 2
Sherborne Student 3
Joan's Father
Joan's Mother
Teacher
Headmaster
MI6 Agent
Military Policeman
Margaret
Electrical Assistant
Woman in Crowd (uncredited)
Ministry Man (uncredited)
Wren (uncredited)
Dancer (uncredited)
Assistant Wren (uncredited)
Crossword Man in Pub (uncredited)
MI6 Agent (uncredited)
Joan Clarke's Friend (uncredited)
Bletchley Park Agent (uncredited)
Passerby (uncredited)
Military Policeman 3 (uncredited)
Civilian (uncredited)
Evacuee (uncredited)
Bletchley Park Operative (uncredited)
MI6 Agent (uncredited)
Police Sergeant White (uncredited)
Crossword Man (uncredited)
First Aid Nurse (uncredited)
German Pilot (uncredited)
German Spy Plane Pilot (uncredited)