In a field near Silbury Hill in Wiltshire, a new formation of crop circles recently appeared. Small groups of walkers tramp past in the driving rain, barely acknowledging the odd patterns in the corn. A few years ago, says Reg Presley, a veteran rock star turned crop-watcher, these hedgerows would have been lined with tourists, the press and television crews.

'Yeah, it's been discredited by all the hoaxing,' he admits sadly. 'But there's still something going on. Seventy-five per cent of the circles are probably hoaxes. I want to know who's doing the other 25 per cent.'

As he goes to take a closer look, a fan in an anorak approaches. 'Are you Reg Presley?' the fan asks in awe. 'Can I have your autograph?' Reg signs his copy of A Guide to Ancient Sites in Britain.

Download the new Independent Premium app Sharing the full story, not just the headlines

Reg, whose band, the Troggs, had a massive hit with 'Wild Thing' in 1966, seems surprised by the attention. 'Occasionally it happens. The more I get into these circles, people recognise me, you know. It's taken over my spare time. It hasn't yet taken over my life, but there's a good chance it might. It's so bloody interesting.'

It's all happening at the moment for Reg Presley. He has his own slot on local cable television, The Reg Presley UFO Show, which reports on the latest sightings and is watched by some 10,000 viewers around his home town of Andover, Hampshire. He is also writing a book on crop circles and UFOs (working title: Wild Things They Don't Tell You). And the Troggs are still in demand, sort of. At the time of this interview, they were set to do a gig in Mansfield leisure centre. What astonishes Reg almost as much as lights in the sky and circles in the corn is the fact that a song he wrote nearly 30 years ago was number one in the charts for the second week - 'Love Is All Around', performed by Wet Wet Wet.

'I knew it was on the soundtrack of the film Four Weddings and a Funeral. But I just didn't realise it would do what it did. I wrote that bloody song down in about 10 minutes.'

That 10 minutes is about to make Reg Presley a good deal richer, though he insists he is comfortable enough without it. He plays down recent reports that suggested he could earn pounds 1m in royalties from 'Love Is All Around'. 'It might make pounds 500,000,' he says.

Whatever the figure, he already knows how he plans to spend it - on finding out what the men in spaceships are trying to tell us with those confounded patterns they keep leaving in the corn.

Reg, 51, wears shades and a navy-blue blazer that hides a generous paunch, while his hands glitter with gold rings. His gravelly voice is testament to his habit of 60 or so Silk Cut a day. But his lifestyle is far from rock 'n' roll. He drives a modest family car and shares a four-bedroom semi in Andover with Brenda, his wife of 32 years, whom he met at a local hop.

Back then he was called Reg Ball, a bricklayer. He still likes to keep his hand in and has built his own garage and barbecue area. They have a daughter, Karen, 30, a beauty therapist, and a son, Jason, 25, an air steward.

Brenda, he says, regards his UFO-mania with bemusement. 'She knows I'm dead keen on trying to find out what's going on. She sits there trying to keep her feet firmly on the ground.'

He reckons his first close encounter with a crop circle came at the age of seven as he grew up in Andover. 'We were playing and decided to go to the plantations - locally known as the plannies - a small wood where we used to cut our arrows and things.

'I remember coming across something in the field. There were two gangs and we played, one in one circle, one in the other.'

He moved to London when the Troggs happened, but he didn't like it much. 'I quickly realised it wasn't a good place to be. I'm a country boy at heart and I like the laid-back way.'

'Wild Thing' was a massive worldwide hit. Reg tells a story a photographer once told him. 'He was in with these people who were going up the Amazon to go into the jungle and make contact with this tribe. They said the best thing they could give the chief was a battery for the radio they gave him last time they were out there. He said they tramped four days, four nights until finally they made it to this tribe.

'The chief met them; they gave him the battery. He gathered the whole tribe round him, and as he put the battery in, it went 'Deeeeerrrm . . . Wild Thing]' . . .' Reg erupts into throaty laughter. 'That song got our names right across the world. But money-wise we were on such bad deals in the Sixties that it wasn't very lucrative. Since then we've got ourselves together and we don't get ripped off so much.'

The Troggs have been going on and off since then, slogging away at clubs. Other band members, guitarist Chris Britton, bassist Pete Lucas, and drummer Dave Maggs, all live locally. They had a brief comeback two years ago when they made an album with REM. And now there's Reg's number one hit.

The royalties, when he gets them, will help fund his preoccupation with extra- terrestials. He estimates he currently spends pounds 5,000 a year on his hobby and is a member of the group Circles Phenomenon Research. But he says he needs more to pay for helicopter surveillance flights and travel to the world's UFO hotspots.

'I looked at my first crop formation in 1990 and after that I was hooked. When I was young and studying to be a bricklayer, with all the arches and things that we had to draw at college, that gave me an insight to know that this was no ordinary wind damage. I knew there was something more technical there.

'If a circle is absolutely perfect, that's one thing. But these were slightly out of true - elliptical, but only slightly.'

When a new circle appears, he and other crop-watchers move in, measuring, taking samples of the crop and sending them off for analysis, and taking aerial photographs.

Reg has files at home on UFO sightings, and has spent many a long night camped out on the hillsides in rolling Wiltshire, watching the skies. Two years ago, he says, he saw one in the Vale of Pewsey. 'I filmed a UFO crossing the valley. It was a light the same brightness as a star, but it was going down in brightness, then up. Very slowly, moving across the valley about three miles from me.

'All of a sudden it came up five times brighter and changed to orange. It remained stationary there - no noise whatsoever. I don't know what it was. The next day there was a crop formation just where this thing had stopped. A triangle shape with circles on the corner.'

Reg Presley believes they are messages from outer space, clues in the corn. He gives a graphic example. 'A 200ft long penis turned up in a crop formation, just by Chequers. Everybody laughed - so did I. What happened was - it was like this . . .' He takes my notebook and executes a sketch of a penis and testicles. 'It went like that. One week after that appeared near the Prime Minister's home, we discovered that the American male had lost half of his sperm count.

'Two months after that it came out that we're losing it over here, too. I don't believe that crop formation was a hoax. I think somebody was trying to tell us something.'

But he is just warming up. Later in the car, as we search for more circles, he continues; people abducted in spaceships; the repetition, throughout the solar system and in stone ruins, of the angle 19.5 degrees; governments, including our own, covering up the existence of UFOs and sending out agents provocateurs to misinform the crop-watchers. And so on.

'I try to keep an open mind on it, but from all the information coming in, it's pointing to one huge big cover-up for some reason,' says Reg devoutly. Would he relish a close encounter? 'I hope I will have the bottle to go through with anything that happens. If they've travelled millions of miles, I'm sure I'm not going to put on my running shorts and trainers and run the other way.'

Talk of visitors from afar brings back the story about the Amazon tribe. Perhaps any alien visitors he might meet will have heard 'Wild Thing', too.

'I wonder?' he says seriously, eyes focusing on the horizon. 'The whole thing's bloody weird.'

(Photographs omitted)