It has clearly been a long day at Glastonbury Fair 1971. Thus far, the audience have been entertained by the "heavy sounds" of the Edgar Broughton Band, whose pièce de résistance, called Out Demons Out, turned out to be less a song than a grimly determined act of attrition, and at points showed every sign of going on for the entire duration of the three-day festival.
They have been lectured on the transience of possessions by a guru, who may have undermined his argument somewhat by being chauffeur-driven to the stage in a Rolls Royce. Then there were some representatives of the Church of England, who got on stage and sang hymns at them until the Edgar Broughton Band seemed like a model of musical economy.
But the fun is far from over yet. The stage has now been commandeered by two audience members, who have decided to favour the crowd with what was once popularly known as a "freeform freakout". It is difficult to see how anything could be freer of form, or indeed more freaked out. Performer number one has some bongos and a harmonica, but performer number two is armed only with a microphone and his distinctive vocal style. "WEAURK!" he screams. "HUYEARK! WAAARGH!"
After a couple of minutes, the cameraman instructed to capture this ground-breaking moment in improvised music wryly pans back to reveal the true horror of the situation: both performers are completely naked from the waist down.
Watching this footage three decades on, in his Somerset editing suite, film director Julien Temple chuckles to himself. He has, he says, seen rather a lot of this sort of thing in the past few months. "And jugglers," he mutters darkly. "I think I've seen every juggler who has ever juggled at Glastonbury."
Temple has spent much of the past three years working on a documentary about the history of the Glastonbury festival, an idea first mooted when the event was forced to introduce the infamous "superfence": "They were really thinking that if it didn't work, if it didn't stop people without tickets getting in, or if ended up negating everything the festival stood for, then Glastonbury would stop, so the idea of making a film came up."
Even for a man who survived making three separate films about the Sex Pistols (1977's short Sex Pistols Number One, The Great Rock'n'Roll Swindle and 2001's exemplary documentary The Filth and the Fury), it has proved a daunting task. He has managed to track down footage, both amateur and professional, of every single Glastonbury: the shelves in his editing room are groaning under a mountain of video-tapes and reels of film. For the past three years, he has sent out crews of his own, in the hope of capturing the elusive "Glastonbury Moment" festival-goers are so fond of talking about, when the music, the bucolic setting and the general atmosphere of bonhomie combine to create a kind of mass transcendence.
The Glastonbury Moment undoubtedly exists, but getting footage of it has proved tricky. "It's difficult to capture," he admits, "especially with a film crew, because the minute a film crew turns up, it's not a moment of transcendence any more, it's some cunt with a camera spoiling everything. The secret weapon is getting festival-goers to shoot film themselves. That's some of the best stuff I've got, when people are just handing around a camera among their friends in the dance tent at night. You couldn't get that sort of blissed-out intimacy if you had a guy with a film camera and microphone obviously making a film. There's a lot of really good moments, human moments and surreal moments and enlightening moments, but you have to dig them out, because they're embedded in a lot of footage of jugglers."
Temple also notes that the tradition of making films about festivals, which reached its zenith in the early 1970s, has hardly produced a string of cinematic masterpieces. The most famous is probably Woodstock, a mammoth documentary that has the same effect on most people as the Edgar Broughton Band's set at Glastonbury 1971: as it plods on and on, you're struck by the fear that you might be watching it for the rest of your natural life.
There have been two previous attempts to make a film about Glastonbury - Nic Roeg's charming but rarely seen Glastonbury Fayre (from whence the footage of the naked freakout came) and a flatly awful mid-90s effort, which succeeded in making the festival look like the most boring event on Earth.
"There's a problem with making a movie for theatrical release that doesn't have a narrative, and a pop festival doesn't really have a narrative," says Temple. "Glastonbury has a very colourful history in terms of the travellers, the quirkiness of the farmer and his garden and how a free-festival, countercultural event has had to adapt to a more corporate and commercial world. They're all interesting, but not really involving enough for the big screen. The film will be looking out from Glastonbury, rather than looking in, so that you really do try and get sense of people's lives evolving over."
Temple and his researchers certainly seem to have come up with vast array of telling material for the film: everything from footage of the first year the internet came to Glastonbury ("They're hooked up to people in San Francisco and there's this genuine sense of innocent excitement about this miracle new invention."), to film of a man "having a hissy fit because the cash machine has broken down, which is pretty ironic considering it was once a free festival".
The problem that faces him now is marshalling it into a watchable social history. "I've got to find some way of telling a fucking story," he nods. "Or I'm in deep shit, which is always possible." He brightens: "Still, at least there's always an element of risk." In true Glastonbury style, the question of a deadline is met with a vague response: "I'm not that bothered when it's finished by ... there's talk of getting it ready for a winter release ... just not this winter."
Instead, Temple mentions screening a 12-hour "rough cut" in the cinema field at next year's festival, then editing that down for a theatrical release. Despite the shelves full of video tapes, he is still apparently on the look out for more footage. "We're actively encouraging people to go there and film it this year. If we use it, we'll pay for it. The more it tells the audience's story, the better it will be."
He returns to the footage of Glastonbury Fair on the screen. Now, the stage has been given over to a vegetarian activist, whose notion of cruelty to animals clearly does not preclude waving a terrified-looking chicken around in front of thousands of cheering hippies. Temple laughs. "Joe Strummer was at the first one as well," he says, "and he became a vegetarian as a result of this. He was converted by this guy with the chicken. You can laugh at it now, but somewhere in that crowd, Joe Strummer is having his life changed forever by Glastonbury."