Encounter Atlas
Why it matters
Britain's equivalent of the Condon Report, kept secret for six years.
Official releases / GBUnited Kingdom
Project Condign: UAP in the UK Air Defence Region
A secret study completed in 2000, released under Freedom of Information in 2006. It analysed about 10,000 sighting reports, found no threat, and suggested most unexplained cases were natural atmospheric plasmas, a theory that drew heavy criticism.