The beginner's guide to Glastonbury

It's that time of year again, when Crusty calls to Dongler across the mystic airwaves, when New Agers and crystal gazers, yogic flyers and digeridoo transcendalists come together in a love-feast of celebration. It's time for the tribals to get together with the ferals, the dreadlocked white folk who live in camper vans, walk enormous lurchers on lengths of hairy string and hang out in cosmically significant fields communing with ancient vibes. From the Finsbury Park Fleadh to the tantric shopping village of the Glastonbury Festival, early summer in Britain can resemble a collective retreat into ancient history, a woad-and-sandals variant of the Sealed Knot organisation that recreates battles of the English Civil War.

It's that time of year again, when Crusty calls to Dongler across the mystic airwaves, when New Agers and crystal gazers, yogic flyers and digeridoo transcendalists come together in a love-feast of celebration. It's time for the tribals to get together with the ferals, the dreadlocked white folk who live in camper vans, walk enormous lurchers on lengths of hairy string and hang out in cosmically significant fields communing with ancient vibes. From the Finsbury Park Fleadh to the tantric shopping village of the Glastonbury Festival, early summer in Britain can resemble a collective retreat into ancient history, a woad-and-sandals variant of the Sealed Knot organisation that recreates battles of the English Civil War.

At the heart of the revels is an event and a destination. The event is the summer solstice - today, the longest day of the year, the day of maximum sunlight (if you're lucky) when the believers turn out on Salisbury Plain to see the sun coming up through the massy trilithons of Stonehenge. And the destination is Glastonbury, a place that's become both real and mythical in the modern mind, a place and a festival plugged into pre-history, a sort of Camelot with patchouli incense.

But hold on, some of us are ingenues in this world. Some of us, whether sceptical or credulous about Stonehenge and Glastonbury, stones and crystals, tribal rites and ancient creed, feel we need guidance. Who is there that we can trust to weigh the exact significance of this tor, this barrow, these twining mythologies? These days, in ancient-mystical circles, it seems you need seek out only one expert.

You find him two hours' drive from London, embedded in a pink manor house in Yatesbury, in the spooky heart of Britain's neolithic past, near the bosomy altar of Silbury Hill, the longbarrows of West Kennett, the White Horse of Uffington and - most important of all, the sacred heart of the ancient mysteries - the stone circle of Avebury. Julian Cope greets you with a cheery wave. He is wearing a peculiar suit in purple houndstooth, without sleeves but with zips and nonsensical straps. With his long streeling hair and shades, he resembles a well-to-do hermit.

But he's not. He bridles slightly at being confused with the crusties, New Agers, hippies, Druids or any other hairy pseuds on the Glastonbury landscape. Hell, he doesn't even believe in ley lines or crystals. "We're not crystal," he explains in his characteristically high-decibel shout, the "we" referring to Dorian, his American wife. "We're rock but we're not crystal. We're barbarians on a pre-Roman trip." Cope, too, was once a sceptic, before his Damascene conversion. "I thought Stonehenge stood for hippies and I was a punk. I thought Stonehenge must be crap. But I was one of those who came to mock and remained to pray. One day I went there and thought, hang on, this is Stonehenge I'm responding to... this is ridiculous." He pauses, awestruck, then explains. "We're brought up to believe that civilisation in Britain started when the Romans came over. But you couldn't have a barbarian culture that could create so much."

He is, however, suspicious of the claims people make for Stonehenge. It's not a Stone Age monument at all: "It's a Bronze Age power statement, built by incomers." And it's not even a temple for the summer solstice. "The way it's psychologically sited, I wouldn't think so. You walk down the avenue and the sunrise is behind you. Which means the winter solstice..."

Cope has bad news, too, for those travelling to this week's Glastonbury festival: that, apart from the Tor, there aren't any true neolithic remains around the site. "When Pope Gregory came in 601 AD, he demanded they destroy the stone circles and build a chapel in their place. Over the years, they would have taken all the old stones away and left people with dry-stone walls to worship." Still, he concedes, "the physicality of the Tor is unbelievable".

He delivers these and other crushing judgements with the utmost confidence. For Cope is the man with the key to all mysteries, a rock star turned academic, antiquary and shaman. He used to have cult fame as the frontman for The Teardrop Explodes, a Sixties-esque psychedelic band that flourished in the early 1980s as a happy alternative to Duran Duran. "We were very anti-New Romantic. We were utopian. We were Dionysian." A 1981 single, 'Reward', was a Top Ten hit but, as chronicled in Cope's autobiography Head-On, the band ingested so much acid and had such epic rows, that it's amazing they stayed together so long. After they split in 1984, he went on to sporadic success as a solo artiste and unclassifiable crackpot. Then, 10 years ago, he became hooked on the study of stone circles and it took over his life.

Today he's happiest being known as the author of The Modern Antiquarian: A Pre-Millennial Odyssey through Megalithic Britain, a vastly ambitious, 450-page gazetteer of every field in the British Isles where Stone Age man might have constructed a rudimentary house, or cut a priapic chalk giant onto the landscape. He is also the figure chosen to take faithful and sceptical alike on an instructive tour d'horizon of mystical Albion in The Modern Antiquarian (7pm, Saturday), part of BBC2's Glastonbury 2000 celebrations.

Nobody embarks on such an odyssey into the past (visiting the book's 300 sites took him eight years) without becoming a little weird and I'm happy to report that, after a series of high-octane lecturettes on the Scando-Germanic language and the many names of Odin, Cope goes into full crackpot mode. "There are so many different ways of having a vision. To achieve your heights, you can often go right down, you can allow your lower self in. I achieve my strongest vision when I go onto the landscape and get down into my Iron Age self, which is the warrior, then my Bronze Age self, which was the coming of the chieftains, then my Stone Age self, the neolithics who built the first temples..."

Cope clearly identifies with the ancient tribes of earth, and writes about them with empathy. He admires their practicality and their closeness to the earth. His own closeness to the mystic clods and stones of his prehistoric sites is alarmingly intense. When not descending into layers of his ancient self, he has transcendental visions. "The physical side of the vision is the strangest thing to explain," he says. "It's a Job-type thing. A third-eye vision is like being anally raped through the middle of your head. It's violent as hell". Indeed.

At these moments, you search Cope's sunglassed face in vain for signs of irony or self-parody. There are none. "I used to be a mocker, a total ironist and I've lost my sense of irony," he says, quite gleefully. He now corresponds with the nation's leading experts in archeology, he's an expert on John Aubrey and William Stukely, the 17th and 18th-century chroniclers of Avebury, and clearly thinks of himself as part of their timelessly eminent company. It all seems a very long way from the catchy pop of Kilimanjaro, his classic first album.

Like Casaubon in Middlemarch, Cope these days is a man determined to find the key to all mythologies, starting with the mysteries on his doorstep. He will celebrate the solstice today on his beloved Avebury Ring, surrounded by the twin circles of ancient megaliths, by stormy mythologies, by picnicking families and ding-donging ice-cream vans. To the south, Stonehenge will be open to the public for the first time in 16 years. In Pembrokeshire, they're looking for someone to blame for the fiasco of the three-ton Millennium Stone which fell out of the boat that was carrying it. At Glastonbury, hundreds of pre-festival groovers will be pondering the significance of the looming Tor, and reading how Joseph of Arimathaea once walked there, quite possibly carrying the holy grail in his napsack.

And Julian Cope will be looking on as, if only for one puzzling day, a phenomenon recurs: the sight of thousands of secular-modern Britons attempting to draw mystic vibrations and rough pagan raptures from England's green and pleasant land.