Hardened Glastonbury-goers are used to incongruous spectacles, from the pristine crooner Tony Bennett playing the main stage to the troubling cult of Rolf Harris. But not even the crustiest veteran could have been prepared for the sight of 91 classical musicians fine-tuning their instruments and squinting at the Somerset sun. English National Opera had come to town with Wagner's Ride of the Valkyries.
As I stood in what opera buffs call the front row - and what rock fans know as the mosh pit - I nudged an audience member by my side and asked him whether he was a regular fan of opera. "Oh yes," he replied, "I love all that stuff. Michael Flatley and all that."
Across the security fence, two curious groups scrutinised each other: on the one side, a formally attired, respectfully seated group; on the other, a mud-caked, huddling mass. The musicians had approached their unusual audience with apprehension. The stand-off was broken by a chant, which grew louder and louder: "ENO, give us a wave, ENO, ENO, give us a wave!" En masse, the orchestra laid their instruments to one side and raised their hands in salute.
As the opening strains filtered through the crowd, some shuffling ensued, but the audience became more enthusiastic as the valkyries appeared on stage, leading the train of bound and gagged dead heroes. Brunnhilde's entrance exposed the practical limitations of playing on the Pyramid stage. Far from the spectacular arrival witnessed in the current performance at the Coliseum in London, here we had less of a stage and more of a thin strip, with the actors bunched up against the main orchestra. It was perhaps unsurprising that the audience's attention slackened somewhat. A couple of conversations broke out, with one audience member asking of another: "Wotan. Is he the same as Odin?" "Nah," came the reply, "different religions."
All of this changed, however, with the arrival of Wotan. Helpfully dressed in a knee-length leather coat and an impish goatee to indicate his villainy, he provoked a chorus of boos. Where at first their attention was largely held by the novelty of the experience, and their familiarity with the motif (popularised by Francis Ford Coppola's Apocalypse Now), the spectators were now immersed in the drama. As Wotan started menacing Brunnhilde, a plaintive, gruff Geordie voice piped up: "Leave her alone!" Brunnhilde lamented the twist of fate that forced her to shelter her half-sister Sieglinde: "You did the right thing!" shouted a middle-aged woman. This rapt attention remained unbroken until the end of the performance - albeit with some occasional confusion. With the passionate reconciliation of Wotan and Brunnhilde, one wag let fly: "Hello! Aren't they father and daughter?"
However tortuous the narrative appeared to the uninitiated, the audience's reaction at the end was remarkable in its unanimity. Opera etiquette was breached by the crowd's incessant cry of "More!" A baffled-looking ENO returned to the stage for three ovations (standing, by default) before retreating backstage, having no encore to play.
The look of bemused gratitude had yet to fade from the faces of the musicians when I spoke to a couple of them after the performance. Gonzalo Acosta, the leader of the orchestra, expressed his delight at the size of the audience (early estimates ran to 50,000). Did he experience any nerves in the build-up - worrying, for instance, that the typical Glastonbury welcome of bottles of urine might be reserved for the orchestra? "Oh no. I find it doesn't help to approach performances any differently. All you can do is perform the music to the best of your ability." Barry Callan, who played an orderly in the production, admitted that he "was absolutely terrified", though "the crowd put us immediately at ease with the roar as we went out". With such a level of support, surely it would be a shame for the occasion to be a one-off? Acosta agreed: "But that's really in the hands of the sponsors now."
Of the recent attempts to popularise opera - cheap tickets at Covent Garden, Raymond Gubbay's failed Savoy Opera - ENO's Glastonbury gig was unique in feeling entirely natural, shorn of the suspicion of social engineering that plagued earlier experiments. And Glastonbury seemed a fitting venue for Wagner: legend has it that King Arthur was buried in Glastonbury, and the Arthurian myth-cycle provided inspiration for Wagner's Parsifal.
Whether the Glastonbury crowd would have been happy to sit through Wagner's complete 17-hour Ring is far from certain. And yet, as tens of thousands milled around humming the Ride and speaking of Wotan and Brunnhilde, Wagner's dream of a City of Dionysus, where, as in ancient Greece, huge crowds gather to hear a performance, didn't seem so far-fetched.
