According to statistics released by the Ministry of Defence this week, only one UFO sighting was recorded in the Bristol area between 1981 and 1996.

For one former RAF fighter pilot and leading ufologist from Winterbourne, the lack of information is just the latest in a high-level cover-up which has been going on for decades.

The solitary sighting in the Bristol area recorded in the newly declassified files happened in Weston-super-Mare in September 1993, when a member of the public informed the MoD in Whitehall that they had seen a mysterious "ball of light" in the sky.

The unnamed person first went to their local police station, where they were advised to write to the MoD to explain what exactly happened between 8.45pm and 9pm at the Bleadon Level near the River Axe.

The letter reads: "A member of our local sporting club and myself were walking away from the sea wall towards our vehicles, when a ball of light the size of a football (a dim not a bright light) came straight towards us, with a rush of air travelling at great speed.

"It was not more than 30 yards high, just to our left. It went straight towards the sea wall and without seeming to stop, just came straight back towards us again from the same way, and disappeared across the level with the same rush of speed.

"Another member of our sporting club was following behind, and when we said to him, 'you will never believe what we have just seen', he described exactly the same experience. I hope this will be of some interest."

No further correspondence is recorded.

The next nearest recording UFO sighting to Bristol was over the jazz tent at the Glastonbury Festival in 1994, when two revellers reported seeing a "twirling set of moving lights attached to what must have been a circular object".

The woman's friend, a metaphysics students, told investigators the same story and the pair drew similar diagrams.

Winterbourne UFO expert Denis Plunkett, 78, who runs the British Flying Saucers Bureau, believes many more unidentified flying object sightings go unreported or are kept secret by the MoD.

He said: "Calls I've had recently include UFOs in Thornbury and Bishopston. However, I actually believe we are in a trough in terms of reported sightings at the moment, compared to the period between the 1940s and 1970s.

"In those times, only 10 per cent of people believed in UFOs, of course. Now 90 per cent of people believe they exist and they know more about the subject.

"I think fewer people are willing to report them to the authorities now. I've had maybe half a dozen sightings reported to me in Bristol over the last two months.

"One particular couple were out in their garden in Bishopston and saw a formation of objects flying from the south west towards the north east, crossing the city completely silently.

"The one in Thornbury was a sighting where a man saw a UFO being chased through the air by a fighter jet.

"That's unlikely to be reported by the MoD, however – I think they're keeping back the more serious ones for security reasons."