United Kingdom
Defence Intelligence files on UFO sightings reported to the MOD, spanning 1948 to 2003. Two series from The National Archives at Kew: DEFE 24 (annual UFO report files and investigation records) and DEFE 31 (Defence Intelligence Staff assessments and policy documents).
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About This Collection
The UK Ministry of Defence maintained a UFO desk from the 1950s until 2009, when it officially closed its UFO reporting programme. Reports from the public and military were filed, assessed for defence significance, and retained in DEFE series files at The National Archives.
The DEFE 24 files are organised chronologically. Early files (1948 onwards) contain post-war sighting reports and assessment correspondence. Later files include the period covered by Nick Pope's tenure at the MOD UFO desk (1991 to 1994), during which the office received several hundred reports annually.
DEFE 31 contains the higher-level assessments, including working papers related to the Condign Report, a classified study completed in 2000 that examined UK UFO data and proposed explanations involving exotic atmospheric plasma phenomena.