PlayThe Ministry of Defence has released its real "X Files" containing accounts of UFO sightings.
Covering sightings from between 1986 and 1992, the 19 files released by the National Archives include a near-miss involving an Alitalia airliner near Lydd in Kent on April 21 1991.
The aircraft was en route from Milan to Heathrow with 57 people on board when pilot Achille Zaghetti saw the strange object some 1,000ft above him.
He shouted: "Look out, look out" to his co-pilot, who also saw the object, it was reported.
A 14-year-old boy reported seeing a missile flying at low level before climbing through the cloud and disappearing on the same evening. There were a number of other similar unexplained incidents recorded the same year.
The MoD also released an account by a US Air Force fighter pilot Milton Torres of an encounter with what he believes was an alien spaceship in the skies over England in the 1950s.
He was warned to keep quiet about the incident, but eventually talked about it 31 years later at a veterans' reunion.
On the night of May 20 1957, Dr Torres, then aged 25, was on standby at RAF Manston in Kent when he received an urgent order to scramble.
He was told to intercept a UFO with "very unusual flight patterns" over East Anglia that radar operators had been tracking for some time.
The pilot was ordered to fire a salvo of 24 rockets at the object but it suddenly darted off and disappeared from view.
Dr Torres, now 77 and a retired professor of civil engineering, said: "I think it was an alien spacecraft. It had a propulsion system that was beyond us - either magnetism or anti-gravity."
The records range from reports by professional pilots to rants about the extraterrestrial menace.
One of the more eccentric letters sent to the department, dated March 1990, was from a woman claiming to be an alien from the planet Spectra.
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