Jeffery, Keith (2010) MI6: The History of the Secret Intelligence Service 1909–1949 London: Bloomsbury, ISBN 978-0-7475-9183-2
Judd, Alan (1999) The quest for C : Sir Mansfield Cumming and the founding of the British Secret Service, London: HarperCollins, ISBN 978-0-00-255901-0
Seeger, Kirsten Olstrup (2008) 'Friendly Fire'(DK)ISBN 978-87-7799-193-6. A biography of the author's father who was a member of the Danish resistance during the Second World War.
Smith, Michael (2010) SIX: A History of Britain's Secret Intelligence Service Pt 1 Murder and Mayhem 1909–1939, London: Dialogue, ISBN 978-1-906447-00-7
Smiley, Colonel David (1994). Irregular Regular. Norwich: Editions Michael Russell. ISBN 978-0-85955-202-8. An autobiography of a British officer, honorary colonel of the Royal Horse Guards, David de Crespigny Smiley LVO, OBE, MC, who served in the Special Operations Executive during World War II(Albania, Thailand)and was a MI6 officer after war(Poland, Malta, Oman, Yemen). Translated in French by Thierry Le Breton, Au cœur de l’action clandestine. Des Commandos au MI6, L’Esprit du Livre Editions, France, 2008 ISBN 978-2-915960-27-3
Tomlinson, Richard; Nick Fielding (2001). The Big Breach: From Top Secret to Maximum Security. Mainstream Publishing ISBN 978-1-903813-01-0