Himself - Narrator
Gordon Welchman (voice)
Herself - Gordon Welchman's Daughter
Himself - Ex-Head of Hut 6, Bletchley Park (1939-1941) (archive footage)
Himself - Author, 'The Secret Life of Bletchley Park'
Himself - Veteran, Hut 6
Himself - Veteran, Hut 6
Herself - Veteran, Hut 6
Himself - GCHQ Historian and Former Analyst
Himself - Vice President, Wolfson College, Cambridge (as Prof John Naughton)
Himself - Chairman, Bletchley Park Trust, and Former Chief, MI6 (as Sir John Scarlett KCMG OBE)
Herself - Gordon Welchman's Granddaughter
Himself - Former President, The MITRE Corporation
Himself - Gordon Welchman's Colleague
Himself - Gordon Welchman's Colleague