This chapter describes the implications of the changes for oversight of the intelligence and security agencies, focusing on the origins and evolution of the UK oversight structure. The period from the end of the Cold War to the present day has been one of dramatic transformation for intelligence oversight in the UK, during which the agencies have emerged from the shadows of secrecy and democratic oversight has become well-established. The introduction of a statutory oversight framework for the agencies in the UK took place during what was in retrospect a short golden interval between the ending of the Cold War and the attacks of 9/11. The Snowden revelations have had a significant impact in the UK, since a number of them concern the work of Government Communications Headquarters and its collaboration with the National Security Agency in bulk collection of communication data.