Steven Mackintosh
Himself - Narrator
Acting
Brian Deacon
Gordon Welchman (voice)
Acting
Rosamund Welchman
Herself - Gordon Welchman's Daughter
Acting
W. Gordon Welchman
Himself - Ex-Head of Hut 6, Bletchley Park (1939-1941) (archive footage)
Acting
Sinclair McKay
Himself - Author, 'The Secret Life of Bletchley Park'
Acting
Jimmy Thirsk
Himself - Veteran, Hut 6
Acting
Asa Briggs
Himself - Veteran, Hut 6
Acting
Jane Fawcett
Herself - Veteran, Hut 6
Acting
Tony Comer
Himself - GCHQ Historian and Former Analyst
Acting
John Naughton
Himself - Vice President, Wolfson College, Cambridge (as Prof John Naughton)
Acting
John Scarlett
Himself - Chairman, Bletchley Park Trust, and Former Chief, MI6 (as Sir John Scarlett KCMG OBE)
Acting
Jennifer Welchman
Herself - Gordon Welchman's Granddaughter
Acting
Robert R. Everett
Himself - Former President, The MITRE Corporation
Acting
Eric Ellingson
Himself - Gordon Welchman's Colleague
Acting
Larry Hill
Himself - Gordon Welchman's Colleague
Acting