In a year without an actual Glastonbury festival, here's a terrifically entertaining substitute. Opening with the almost inevitable sound of wellies sloshing through mud, Glastonbury, Julien Temple's documentary collage of recent and archive footage, stays true to the festival's ethos of letting it all hang out. Where Woodstock sought only to chronicle - as its subtitle had it - "Three Days of Peace and Music", Temple's survey spans the decades to give an understanding of Glastonbury's changing nature. Gone are the days when acid-buoyed guests were serenaded by the likes of Melanie; in recent years, the carnival has followed a rather different direction, erecting steel walls to keep out unwanted gatecrashers, and granting the Manic Street Preachers their own private facilities backstage. Corporate logos jostle and vie with the resident wild and crazy horses.
Headline acts include Morrissey, Bowie, Björk and Radiohead, but a deliberate, just-loose-enough structure preserves a sense of what it might be to stumble across an impromptu happening in some far-distant field, or wander into the wrong tent at the right time. Best of all: there's no Jo Whiley. The keynote is diversity: of people, of opinions, of performance. There's something to be said in favour of any doc that can bring together, within moments of screen time, the triumphant appearance of Rolf Harris, a segment on how sewage is removed from the site, and Joe Strummer encouraging the crowd to smash up CCTV cameras during a rendition of "Straight to Hell".
And yet, for all the harmony this implies, Temple never loses track of the tensions that exist in and around these fields: between those who come to express political solidarity, and those who just want to get drunk; between the naked hippies and tetchy Druids, and those braying toffs who refer to the festival as "Glasters", sing cluelessly along to Pulp's "Common People", and very likely deserve to be shot. Priceless archive news footage finds a young John Craven standing cross-armed in a meadow, reflecting on what Glastonbury's excesses might mean for "the straight society", while a monochrome old dear dismisses the festival crowds as rife with "filth and flies".
But it's precisely that filth and fury that gets an old punk like Temple going, you sense, and he was never going to be anywhere other than firmly on the kids' side: watch as he juxtaposes a bullet-headed security raid with the sounds of Primal Scream performing "Swastika Eyes". More soberly and charmingly, though, we also find festival figurehead Michael Eavis roaming among the tents and spectacle, and agreeing with one punter's assessment that the whole event's "a bit overrated". It's as close to the spirit of this most idiosyncratic of British institutions as audiences are likely to get sitting in a darkened room with all their clothes on and fully-functioning plumbing close at hand.
Glastonbury screens on BBC2 tomorrow night at 11.30pm.