But another intriguing finding to emerge from the 1981-1996 archives was a surge in reports at the time of UFO-related blockbusters such as 1996's "Independence Day," not to mention the British television run of "The X-Files."
Among the most striking accounts released by the Ministry of Defence (MoD) is that of two boys who reported being spoken to by an alien with a lemon-shaped head, who appeared before them in a field on May 4, 1995.
"We want you, come with us," said the alien's voice, according to a police report filed after the youngsters, who seemed "agitated and distressed," recounted their experiences.
"They stated the object was about four houses high in the sky and about forty foot away from them," said the report, adding that when officers went to check two days later, they found only a farmer spraying his crops.
In another account bound to excite ufologists, a former armed forces chief urged authorities to take more seriously a report by US Air Force (USAF) staff near an airbase in eastern England.
The individuals "reported seeing a strange glowing object in the forest," said a report by a US air force commander, recounting what three of his staff told him of the incident, early on the morning of December 27, 1980.
"It illuminated the entire forest with a white light. The object itself had a pulsing red light on top and a bank of blue lights underneath. The object was hovering or on legs. As the patrolmen approached the object, it manoeuvred through the trees and disappeared."
Then there is the report of how, between November 1989 and April 1990, the Belgian air force scrambled F-16 fighter jets to investigate a series of UFO sightings -- and reportedly "locked on" to them with their radars.
"The mystery remains unresolved," wrote General Wilfried de Brouwer, Chief of Operations, Belgian Air Staff, adding that despite being sceptical, "the evidence was remarkable."
One of the spookiest incidents occurred in the early hours of July 15, 1996, when a UFO was spotted hovering over a cemetery in Widnes, northwest England, before firing burning laser beams into the ground.
Cynics would note that the man involved was heading home from a night out at the time -- possibly in a similar mental state to two revellers who claimed to have seen a UFO hovering over the jazz tent at the 1994 Glastonbury Festival.
And sceptics will also point to a more general trend made clear by the latest archives.
In 1995 there were 117 UFO sightings reported to authorities, but this spiked to 609 in 1996, according to the MoD reports, released after a three-year project with the National Archives.
"It's evident there is some connection between newspaper stories, TV programmes and films about alien visitors and the numbers of UFO sightings reported," said UFO expert and journalism lecturer David Clarke.
"Aside from 1996, one of the busiest years for UFO sightings reported to the MoD over the past half century was 1978 -- the year 'Close Encounters of the Third Kind' was released," added Clarke.
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