IT'S drizzling on a grey Saturday morning and the leafy university campus is deserted.

That's except for the main auditorium, where hundreds of people stream into a lecture theatre where the air is thick with theories and dire warnings, including that next year's Olympics will be an Independence Day-style bloodbath.

This is the Exopolitics Expo in Leeds last weekend - the UK's largest UFO conference.

Among the 300 attendees at the three-day event are computer programmers, full-time mums, engineers and even a police detective constable.

But they all have one thing in common - they are all fascinated by the idea that governments are covering up the existence of aliens - and other things besides.

There are stalls selling everything from healing aura scent sprays to DVDs explaining how the world is controlled by influential cartels hell-bent on global domination.

The notion that the Government is covering up the truth is the strongest theme in Ian Crane's DVD stall at the expo. Dad-of-three Ian, 55, is hoping to spread the word that the closing ceremony of the 2012 Olympic Games on August 12 could be a target for a full-scale "alien invasion".

He said: "I think it will be the perfect setting for a 'false flag' invasion, in other words the event will be made to look like an extra-terrestrial invasion but in fact it will be a deception and really the work of the world's governments, to keep us all living in fear.

"I don't care if people call me a nutter, I hope that by spreading the word about what's going to happen I can help save thousands of lives."

"If enough people know about it in advance then the attack will not be carried out. I'm simply sowing the seed in the mind of the public."

Full-time mum Brigitte Barclay has travelled to the conference from her home in Devon.

She may be recognisable to some Sun readers, as in the late Eighties and early Nineties she was one the paper's most popular Page 3 girls.

Brigitte, 40, also posed for Playboy and Penthouse.

But after giving up modelling she moved to LA where she worked as a make-up artist and, she says, had alien encounters.

Brigitte, who founded a support group for other people who have seen UFOs, is here today to share her story.

She told The Sun: "I've always seen UFOs, since I was a little girl. I've had 17 sightings altogether.

"People write off what I'm talking about as nonsense and one bloke even told me I must be on LSD but my memories and things I've seen were real. The information is out there if you want to read it, and for people to just say this didn't happen to me is ignorant."

Brigitte was driving to a colleague's house in February 1993 when she had one of her most memorable ET encounters.

She recalls: "I'd come off the freeway exit in Brentwood, LA, near the Holiday Inn hotel, when I got a sudden feeling of nervous energy like butterflies in my stomach, and I knew something was going to happen.

"I saw a 50ft craft about five metres away. It had no wings but a glowing orange light underneath it. It was right in front of me and I was gripping the steering wheel very tightly.

"I felt myself being sucked through the car and suddenly I was in a field with three beings and a child. They were around 6ft tall, naked with iridescent, shimmering skin and pieces of white hair. Their energy was amazing and I didn't feel scared. There was no talking or conversation, I just felt a strong bond with them.

"Then all of a sudden I was back in the car."

Conference organiser Anthony Beckett, 35, from Skipton, North Yorks, is one of the few people I meet who hasn't had an alien encounter.

"I don't think we're oddballs, as UFOs and extra-terrestrial life are questions everyone has considered," he explains.

Not that Anthony should care - with tickets selling at £99 for a three-day pass, the organisers are quids-in whether flying saucers turn out to be real or imaginary.