This programme traces the development of the "state secret". In the twentieth century Secrecy became known as the British disease. We even kept secret the fact we were keeping secrets. Tiffany looks at the growth of the Official Secrets Act which sought to control access to information which the state judged to need withholding. Visits the National Archives as new MI5 files are disclosed for the first time Tiffany finds out why a certain amount of state secrecy is essential.

Produced by Kate Bissell. Show less