The UK's oldest UFO sighting has been revealed as the first ever 'X-file' is unearthed.
It was first spotted 280 years ago when physician Cromwell Mortimer, the secretary of the Royal Society, spotted a ball of light in the sky as he left work.
He was walking home to Westminster, central London in December 1742 and recorded what he witnessed in a scientific UFO report.
The physician jotted down a sketch of the mystery object and published it in the Philosophical Transactions, vol XLIII in 1746, which has just come to light for the first time.
Mr Mortimer wrote: "As I was returning home from the Royal Society to Westminster, on Thursday, December 16, 1742, at 20:40, being about the middle of the parade in St James's Park.
"I saw a light arise from behind the trees and houses in the south by west point, which I took at first for a large skyrocket.
"But when it had risen to the height of about 20 degrees, it took a motion nearly parallel to the horizon, but waved in this manner, and went on to the N by E point over the houses."
As Mr Mortimer watched the object, he believed its path had brought it directly over the Bloomsbury district of London, passing over Queen's Square and making its way in the direction of the canal adjacent to it.
Mr Mortimer said that he "lost sight of it over the Haymarket".
Describing the way it moved, he wrote: "Its motion was so very slow, that I had it above half a minute in view; and had time enough to contemplate its appearance fully."
He drew a diagram showing the weird object, based on this, he explained the mechanics of the object as follows: "A: seemed to be a light flame, turning backwards from the resistance the air made to it.
"BB: a bright fire like burning charcoal, enclosed as it were in an open case of which the frame CCC was quite opaque: like bands of iron.
"At D issued forth a train, or tail of light flame, more bright at D, and growing gradually fainter at E, so as to be transparent more than half its length.
"The head," he concluded, "seemed about half a degree in diameter; the tail near three degrees in length, and about one-eighth of a degree in thickness."
Various theories to explain the UFO range from ball lightning to a meteor, but they don't appear for more than a few seconds.
The sighting remains a mystery almost three centuries on.
British UFO expert Steve Mera said: "It is the first of it's kind. Folk stood out on a balcony witnessed it.
"These folk were well to do which encouraged proper research into it."
