In 1889, the first Official Secrets Act was passed, creating offences of 'disclosure of information' and 'breach of official trust'. It limited and monitored what the public could, and should, be told. Since then a culture of secrecy has flourished. As successive governments have been selective about what they choose to share with the public, we have been left with a distorted and incomplete understanding not only of the workings of the state but of our nation's culture and its past. In this important book, Ian Cobain offers a fresh appraisal of some of the key moments in British history since the end of WWII, including: the measures taken to conceal the existence of Bletchley Park and its successor, GCHQ, for three decades; the unreported wars fought during the 1960s and 1970s; the hidden links with terrorist cells during the Troubles; the sometimes opaque workings of the criminal justice system; the state's peacetime surveillance techniques; and the convenient loopholes in the Freedom of Information Act. Drawing on previously unseen material and rigorous research, The History Thieves reveals how a complex bureaucratic machine has grown up around the British state, allowing governments to evade accountability and their secrets to be buried.