Steven Mackintosh

~ as ~

Himself - Narrator

Brian Deacon

~ as ~

Gordon Welchman (voice)

Rosamund Welchman

~ as ~

Herself - Gordon Welchman's Daughter

W. Gordon Welchman

~ as ~

Himself - Ex-Head of Hut 6, Bletchley Park (1939-1941) (archive footage)

Sinclair McKay

~ as ~

Himself - Author, 'The Secret Life of Bletchley Park'

Jimmy Thirsk

~ as ~

Himself - Veteran, Hut 6

Asa Briggs

~ as ~

Himself - Veteran, Hut 6

Jane Fawcett

~ as ~

Herself - Veteran, Hut 6

Tony Comer

~ as ~

Himself - GCHQ Historian and Former Analyst

John Naughton

~ as ~

Himself - Vice President, Wolfson College, Cambridge (as Prof John Naughton)