Established by the Ministry of Defence with the guidance of Sir Henry Tizard, this working group was the UK's first official study of UFO phenomena. The working party secretly reviewed radar and visual reports, ultimately producing a deeply skeptical report concluding that UFOs were misidentifications, hoaxes, or delusions. The report heavily influenced UK Air Ministry policy for decades, contributing to a long-running official posture of dismissal towards UFO reports. It remained classified for over fifty years and was first released to the National Archives in 2001 following a Freedom of Information request. Its existence had been denied for much of the Cold War, and its declassification confirmed the UK had conducted a formal government study earlier than was previously believed.