Alan Turing

Benedict Cumberbatch

Joan Clarke

Keira Knightley

Hugh Alexander

Matthew Goode

John Cairncross

Allen Leech

Det. Robert Nock

Rory Kinnear

Stewart Menzies

Mark Strong

Peter Hilton

Matthew Beard

Commander Denniston

Charles Dance

Jack Good

James Northcote

Young Alan

Alex Lawther

Sergeant Staehl

Tom Goodman-Hill

Superintendent Smith

Steven Waddington

Charles Richards

Jack Tarlton

Keith Furman

Ilan Goodman

Christopher Morcom

Jack Bannon

Helen

Tuppence Middleton

Sherborne Student 1

Dominic Charman

Sherborne Student 3

Charlie Manton

Sherborne Student 2

James G. Nunn

Sherborne Student 1

Dominik Charman

Teacher

Andrew Havill

Joan's Father

David Charkham

Headmaster

Laurence Kennedy

MI6 Agent

Tim van Eyken

Joan's Mother

Victoria Wicks

Margaret

Miranda Bell

Electrical Assistant

Tim Steed

Military Policeman

Will Bowden

Woman in Crowd (uncredited)

Hayley Joanne Bacon

Ministry Man (uncredited)

Nicholas Blatt

Wren (uncredited)

Ancuta Breaban

Dancer (uncredited)

Alex Corbet Burcher

Assistant Wren (uncredited)

Grace Calder

Crossword Man in Pub (uncredited)

Richard Campbell

MI6 Agent (uncredited)

Daniel Chapple

Joan Clarke's Friend (uncredited)

Lisa Colquhoun

Bletchley Park Agent (uncredited)

Alexander Cooper

Passerby (uncredited)

Leigh Dent

Military Policeman 3 (uncredited)

Sam Exley

Civilian (uncredited)

Dennis Good

Evacuee (uncredited)

Debra Leigh-Taylor

Bletchley Park Operative (uncredited)

Stuart Matthews

MI6 Agent (uncredited)

Joseph Oliveira

Police Sergeant White (uncredited)

David G. Robinson

Crossword Man (uncredited)

Mark Underwood

First Aid Nurse (uncredited)

Nicola-Jayne Wells

German Spy Plane Pilot (uncredited)

Joshua Wichard