The UK government’s UFO investigation programme, documented on gov.uk and at the National Archives (TNA), ran continuously from the early 1950s to 2009. KEY HISTORY: Winston Churchill ordered the first official investigation after RAF pilots reported unexplained aerial phenomena post-WWII. The Flying Saucer Working Party was established 1950. DI55 — a SECRET branch of the Directorate of Scientific and Technical Intelligence — inherited defence-significance cases in 1967. DI55 was part of the Defence Intelligence Staff (DIS) and its primary mission was monitoring Soviet ballistic missiles and space weapons. 11,000+ UFO reports logged by DI55, S4(Air), and other MOD branches between 1959 and 2007. Nick Pope (MOD UFO Desk 1991-1994) wrote “Open Skies, Closed Minds” (1996) after his tour. CIA INFLUENCE DOCUMENTED: The National Archives briefing note states CIA policy “was to debunk the subject and restrict the release of information to the public about UFO sightings made by the armed services” and “American influence upon the team’s methodology can be seen in the conclusions.” The 1978 DI55 briefing — given before the 1979 House of Lords UFO debate — contained scientists internally swapping opinions on whether some UFOs could be genuine extraterrestrial visitors. This internal scientific debate was classified while DI55 publicly deflected. The West Freugh 1957 incident: UFOs tracked by multiple trailer-mounted radar units at an RAF bombing range in southern Scotland — led to questions in Parliament and at the Joint Intelligence Committee. MOD UFO Desk formally closed December 1, 2009, citing “no defence purpose.” DI55 had actually shut down its UFO unit in 2000 after Project Condign.