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

James G. Nunn

Sherborne Student 2

David Charkham

Joan's Father

Victoria Wicks

Joan's Mother

Andrew Havill

Teacher

Tim van Eyken

MI6 Agent

Will Bowden

Military Policeman

Tim Steed

Electrical Assistant

Nicholas Blatt

Ministry Man (uncredited)

Ancuta Breaban

Wren (uncredited)

Grace Calder

Assistant Wren (uncredited)

Daniel Chapple

MI6 Agent (uncredited)

Alexander Cooper

Bletchley Park Agent (uncredited)

Dennis Good

Civilian (uncredited)

Debra Leigh-Taylor

Evacuee (uncredited)

Stuart Matthews

Bletchley Park Operative (uncredited)

David G. Robinson

Police Sergeant White (uncredited)

Mark Underwood

Crossword Man (uncredited)