This article provides a systematic analysis of post-war government policy towards the history of secret services. It focuses particularly upon the problem of preserving secrecy and argues that official history was an instrument through which government sought to address public pressure for the release information, while also extending a degree of control. It shows how the authorities enjoyed some initial success in cloaking the most significant wartime activities, including signals intelligence and organised strategic deception. However, this secrecy was eventually eroded by ‘insiders’, armed with privileged information and near-immunity from prosecution under the Official Secrets Act. Once the existence of these secret activities had seeped into the public domain, officials were increasingly inclined to deploy official accounts of intelligence successes during the Second World War in order to offset some the more embarrassing debacles of the Cold War. These included the story of treachery by the double-agent Kim Philby which received wide publicity in the late 1960s. The article argues that there is substantial evidence of policy-learning in the matter of official history, explicable in part by the presence of officials who handled similar issues over long periods of time. This was exemplified by Burke Trend, Cabinet Secretary to Prime Ministers Harold Wilson and then Edward Heath. It is suggested that secret services have always enjoyed an adversarial relationship with historical researchers. However, official history, although bringing its own difficulties, offered government a middle way and an opportunity of making a positive response to the problems of policing the past.