For decades, they have been scanning the skies for signs of alien activity.
But having failed to establish any evidence for the existence of extraterrestrial life, Britain's UFO watchers are reaching the conclusion that the truth might not be out there after all.
Enthusiasts admit that a continued failure to provide proof and a decline in the number of "flying saucer" sightings suggests that aliens do not exist after all and could mean the end of "Ufology" – the study of UFOs – within the next decade.
Dozens of groups interested in the flying saucers and other unidentified craft have already closed because of lack of interest and next week one of the country's foremost organisations involved in UFO research is holding a conference to discuss whether the subject has any future.
Dave Wood, chairman of the Association for the Scientific Study of Anomalous Phenomena (Assap), said the meeting had been called to address the crisis in the subject and see if UFOs were a thing of the past.
"It is certainly a possibility that in ten years time, it will be a dead subject," he added.
"We look at these things on the balance of probabilities and this area of study has been ongoing for many decades.
"The lack of compelling evidence beyond the pure anecdotal suggests that on the balance of probabilities that nothing is out there.
"I think that any UFO researcher would tell you that 98 per cent of sightings that happen are very easily explainable. One of the conclusions to draw from that is that perhaps there isn't anything there. The days of compelling eyewitness sightings seem to be over."
He said that far from leading to an increase in UFO sightings and research, the advent of the internet had coincided with a decline.
Assap's UFO cases have dropped by 96 per cent since 1988, while the number of other groups involved in UFO research has fallen from well over 100 in the 1990s to around 30 now.
Among those to have closed are the British Flying Saucer Bureau, the Northern UFO Network, and the Northern Anomalies Research Organisation.
As well as a fall in sightings and lack of proof, Mr Wood said the lack of new developments meant that the main focus for the dwindling numbers of enthusiasts was supposed UFO encounters that took place several decades ago and conspiracy theories that surround them.
In particular, he cited the Roswell incident, in 1947 when an alien spaceship is said to have crashed in New Mexico, and the Rendlesham incident in 1980, often described as the British equivalent, when airmen from a US airbase in Suffolk reported a spaceship landing.
Mr Wood added: "When you go to UFO conferences it is mainly people going over these old cases, rather than bringing new ones to the fore.
"There is a trend where a large proportion of UFO studies are tending towards conspiracy theories, which I don't think is particularly helpful."
The issue is to be debated at a summit at the University of Worcester on November 17 and the conclusions reported in the next edition of the association's journal, Anomaly.
The organisation, which describes itself as an education and research charity, was established in 1981. Its first president was Michael Bentine, the comedian and member of the Goons.
It contains both sceptics and believers in UFOs and has been involved in several notable sightings and theories over the years.
Its current president Lionel Fanthorpe has claimed in its journal that King Arthur was an alien who came to Earth to save humans from invading extraterrestrials.
The summit follows the emergence earlier this year of the news that the Ministry of Defence was no longer investigating UFO sightings after ruling there is "no evidence" they pose a threat to the UK.
David Clark, a Sheffield Hallam University academic and the UFO adviser to the National Archives, said: "The subject is dead in that no one is seeing anything evidential.
"Look at all the people who now have personal cameras. If there was something flying around that was a structured object from somewhere else, you would have thought that someone would have come up with some convincing footage by now – but they haven't.
"The reason why nothing is going on is because of the internet. If something happens now, the internet is there to help people get to the bottom of it and find an explanation.
"Before then, you had to send letters to people, who wouldn't respond and you got this element of mystery and secrecy that means things were not explained.
"The classic cases like Roswell and Rendlesham are only classic cases because they were not investigated properly at the time."
But Nick Pope, who ran the MoD's UFO desk from 1991 to 1994 and now researches UFO sightings privately, said there was a future for the subject: "There's a quantity versus quality issue here.
"So many UFO sightings these days are attributable to Chinese lanterns that more interesting sightings are sometimes overlooked.
"The same is true with photos and videos. There are so many fakes on YouTube and elsewhere, it would be easy to dismiss the whole subject out of hand.
"The danger is that we throw out the baby with the bathwater. And as I used to say at the MoD, the believers only have to be right once."
