Sainthood in Cornwall is a family business, founded by St Petroc and passed on to his two dozen children with names that wouldn't mean much to a Vatican hagiographer but survive on the map of south-west England. One is St Endelienta, aka Endellion, whose church stands on an isolated hill a few miles inland from Port Isaac. And it was here in 1958 that a group of Cambridge undergraduates on a reading party stopped to sing madrigals to the locals - who bore it stoically and asked them back the following year. Suddenly St Endellion had a festival. And it still does - of a rare kind that runs more as a community of friends than a commercial enterprise. Like Dartington, it blurs the boundaries between audience and performers, amateurs and pros. And twice a year - Easter and summer - a hard-core of several hundred Endellionites invade this otherwise quiet corner of the world, turning themselves into an ad hoc choir and orchestra, and catching what they can of rural communality between rehearsals. Nobody, however grand, gets paid: it's all done for love. And it could easily be brushed aside as an English middle-class equivalent of Marie Antoinette milking cows but for the fact that the artistic standards are so high - set with exacting seriousness of purpose by conductor Richard Hickox, who has presided over the festival for 26 years.

From a handful of rehearsals, Hickox pulls together an impressive two- week programme, shoe-horned into St Endellion Church which is compact but not the best acoustically. But Endellion has other qualities - not least, a collective will to make each concert an Event. And it was last weekend, in a batch of programmes that were bold, ambitious never routine. They included composer Eleanor Alburga playing her own music for violin and piano; a bizarrely lugubrious Johann Strauss arrangement made for piano septet by Arnold Schoenberg (!); and choral music by two figures destined to be confused for ever more, John Taverner (16th-century contrapuntalist, master of the English florid style) and John Tavener (20th-century holy minimalist, rediscoverer of Byzantine tradition).

Tavener - the living one - was present for the premiere of a new piece for soprano and strings that sounded, in its spaciously ecstatic way, like all Tavener's old pieces: locked into the primordial perfection which, he believes, releases him from any artistic duty to move on. But that said, Tavener still deals in beauty; and the mesmerising repetitions of Song of the Angel worked their predictable magic thanks to the singer Patricia Rozario, a Tavener specialist who knows the style - and the extended range and Semitic souk-stained vocal colouring which it demands.

As a community event, the focus of every St Endellion Festival is something for chorus, either oratorio or opera. And there was much debate in the pubs of north Cornwall last weekend concerning which category truly applies to Vaughan Williams's Pilgrim's Progress - the massive undertaking that drew an overflowing audience on Sunday.

Assembled in the late 1940s from fragments written during the previous three decades, Pilgrim's Progress has the unwieldy, epic bulk of a pageant-spectacle by Mussorgsky, with a quick-turnover cast of thousands who rarely, if ever, blossom into real character. The mood is contemplative, the subject spiritual; and on the score Vaughan Williams hedged his bets, calling it a "Morality" rather than an "Opera". But he was adamant that the piece should be staged in a theatre rather than done devotionally in church. And for that reason, RVW's representatives took some persuading to allow the St Endellion concert performance to take place.

Personally, I think that he and they were wrong. The theatre of the Pilgrim is a theatre of the mind: its pace and contour determined by musical rather than visual imperatives, subsuming the detail of the drama into a cohesive continuum of sound. The characters never quite engage each other: their address is outward to the audience, their "interactions" almost always framed by instrumental linkage. This is not the stuff of staging. It, at best, belongs on radio.

But it certainly belonged at St Endellion. Maybe the circumstances were a touch rough and the sound-space cramped, but Richard Hickox has a genius for this kind of repertory. He understands how to magnify its strengths and camouflage its weaknesses: where to indulge and where control. He also knows how to get the best from soloists who may not be superstars but respond to the right circumstances with singing of real calibre. And here they included Catherine Pierard, Pamela Helen Stephen, and Roderick Williams as the Pilgrim: an acute voice, keen with wiry, fierce intelligence.

As a critic, I respond to the right circumstances too, and I admit that I was captivated by St Endellion: everything about it, from the landscape to the genial company. But also, for purely musical reasons, this Pilgrim was the most momentous, meaningful and utterly engaging thing I've heard in concert or on stage all year. As the Pilgrim reached the end of his journey - to the sound of a full choir, Heavenly Voices (dixit RVW), and a solo trumpet two feet from my right ear - I felt not just deaf, but humbled by the sheer transcendent splendour of it all: convinced that Pilgrim is a great work and a true festival conception, and convinced that it speaks truest and most movingly as a community event like this. When Hickox conducts the piece at the Barbican in November - semi-staged under the aegis of the Royal Opera - it will be interesting to see if he can duplicate the power.

Bach's B Minor Mass was, like Pilgrim's Progress, a piece assembled late in life from earlier-written fragments; and they supplied the highlight of the Proms this week in a performance by Trevor Pinnock's English Concert that circumvented my usual reservations about period bands in the Albert Hall. He used a large ensemble, with wind-doublings that Bach wouldn't have expected. But, since Bach wouldn't have expected 5,000- seat venues either, that strikes me as a perfectly reasonable compromise. The scaling-up, and Pinnock's vital, pugilistic platform style, gave substance to the Sanctus; the Qui Tollis of the Gloria proved just the sort of out- of-body experience it should (albeit slightly out of synch as well). And there was finely focused singing from the soloists, especially Gerald Finley.

Monday's Proms commission involved another, less fortuitous engagement with the echoing spaces of the Albert Hall. The Red Act Arias was one of those pieces where live performance and pre-recorded tape interact, pitching the voices of the BBC Singers against themselves in bursts of processed sound that encircled the auditorium through banks of speakers. Written by Roger Reynolds, the American veteran of electronic music, and conducted by his compatriot Leonard Slatkin, the pre-compositional procedures had clearly been complex, with a long list of systems developers, audio engineers and other support personnel credited in the programme; and no doubt it was impressive as a feat of technical prowess. But, insofar as it was also an attempt to out-Birtwistle Birtwistle (Reynolds's exact contemporary) by composing a poetry of machines, it failed. There wasn't the invention, imagination or the substance to explain its length. Why was it written? Irresistible compulsion? Inner need? I think not. This was mathematics with a musical veneer: a show of strength in academia but nothing for a concert audience.