Well, Rolf Harris had 80,000 festival-goers singing along to every word of songs like Two Little Boys and Jake the Peg in the same year that I took the first of three NS roadshows to Glastonbury. And these days the annual gathering on Michael Eavis's west country dairy farm has become such an accepted part of the social and cultural mainstream that it counts The Guardian/Observer among its regular sponsors and a NatWest bank cash machine among the essential services provided on site.

Above all, though -- and despite its increasingly commercial orientation -- Glastonbury remains a unique opportunity to reach what is probably the largest concentration of socially-aware, radically-oriented people to assemble in Britain outside the really major protest demonstrations. And whereas on a demo the best any activist with a cause to promote can hope for is to give someone a leaflet or sell them a paper, at Glastonbury people have time on their hands -- time to talk, listen and learn. As well as the festival's favoured "good causes" -- Oxfam, Wateraid and Greenpeace being the principal beneficiaries of this year's profits -- organisations such as Amnesty, CND, Unison, Anti-Slavery International and the whole plethora of organisations that set up shop on Glastonbury's Green Fields have long recognised the benefit of taking their message to the mud-stricken masses.

The problem has become that, for the past two years at least, there has simply been too much mud and too many masses. This year's festival sold a record 100,000 tickets -- which, in combination with the fourth-wettest June this century, was a certain recipe for Somme-like scenes in the otherwise lovely Vale of Avalon. Even a relatively secluded and protected spot, such as the Greenpeace field, was trampled and churned to such an extent that the "rainforest effect" it was meant to simulate, having been temporarily planted with 500 young birch trees, far more closely resembled the sort of flooding, mudslides and general environmental degradation that follows deforestation than any tropical idyll that we might be moved to want to save. As an advertisement for environmentally-sensitive campaigning organisations, it did them about as much good as all those pictures of rainforests burning do for the image of the logging companies.

Of course you can't control the weather, and those of us who love what Glastonbury has to offer will continue to make the most of whatever the gods elect to throw at us. Yet Glastonbury's sea of mud over the past two summers is no more an act of god than the destruction of the rainforests. It rained at previous festivals, too (including at least one festival in the 1980s when it was every bit as wet as the last two). But the sheer weight of numbers of people attending during the last two years' rainstorms has turned the entire site, and not just the most heavily used parts of it, into an environmental disaster zone. The land simply can't cope with the strains being imposed upon it.

Nor is it just a matter of Glastonbury becoming a victim of its own success. It is true that, given current levels of interest in the festival, it would probably be possible to double the number of tickets sold, and that every year Michael Eavis has to perform a balancing act between the numbers wanting to attend and the numbers that the site and its facilities can accommodate. This is partly to do with the fact that it is by far the best event of its kind. But it is also that it is virtually the only event of its kind. Most of the other summer events that call themselves "festivals" are little more than outdoor music performances by leading bands. They have neither the range of Glastonbury (with more than 1,000 different acts, including circus, theatre, comedy and cabaret, as well as the musical headline-makers) nor its ancillary markets, stalls and other activities.

For Glastonbury is the sole -- and in some ways monstrous -- relic of what used to be a thriving small-festival scene. Instead of one huge, environmentally-destructive mega-event, there was at one time a summer circuit of festivals stretching from the spring to autumn equinoxes. Most were no bigger than a few hundred people. Some, most notably the Stonehenge Free Festival, which attracted 30,000 people in 1984, grew a lot larger than that and brought associated (though vastly exaggerated) problems along with them.

None of them merited the outright suppression that took place, starting with the "Battle of the Beanfield" in 1985, when the police deployed what the Earl of Cardigan, secretary of the Marlborough Conservative Association, called "unspeakable" violence against a defenceless convoy of people attempting to travel to Stonehenge, and culminating in the Criminal Justice Act, with its massive restrictions on a whole range of civil liberties, including those associated with the organisation of outdoor music events, a decade later.

It's not just rain that has resulted in the last two Glastonbury festivals almost drowning under a sea of mud; the illiberal reign of the past two decades has contributed a great deal by swamping the alternatives to Glastonbury too. Remember that if you were one of those wading through the mud last weekend.