This is the Col. Halt case. Air Force
security
police encounter with landed craft in Rendlesham Forest, physical
evidence (Section II).
Wikipedia note:
The Rendlesham Forest Incident is the
name given to a series of reported sightings of unexplained lights and
the alleged landing of an extraterrestrial spacecraft in
Rendlesham Forest, Suffolk, England in late December 1980. It is
perhaps the most famous UFO event to have happened in Britain, ranking
amongst the best-known UFO events worldwide. It has been compared to
the Roswell UFO incident in the United States and is commonly referred
to as "Britain's Roswell" or the "English Roswell".
Following the event, the Ministry of
Defence (MoD) denied that it posed any threat to national
security
and stated that it was thus never investigated as a security matter.
Later evidence indicated that there was a substantial MoD file on the
subject and this led to claims of a cover-up. Some interpreted this as
part of a larger pattern of information suppression concerning the true
nature of unidentified flying objects, by both the United States and
British governments (see the UFO conspiracy theory). However, when the
file was released in 2001 it turned out to consist mostly of internal
correspondence and responses to inquiries from the public, and
therefore confirmed that the case was never taken seriously by the MoD.