I was lucky enough to go to the first performance yesterday of the new production of the St Matthew Passion at Glyndebourne. At Glyndebourne? Yes - it was a fully staged production, directed by Katie Mitchell.

My expectations were mixed. The cast - the peerless Mark Padmore as the Evangelist, and Sarah Connolly, a singer I would cross continents to hear (as I have done) - looked first class. But I have yet to see a Katie Mitchell production I did not find pretentious. Her Three Sisters and Seagull at the National were raved about. I loathed them, and walked out of both at the interval. To me, they represented everything wrong with so many Chekhov productions. Dark, brooding, portentous and SLOW. Why do so many directors ignore the sheer humour in Chekhov?

I digress. I saw the Jonathan Miller staged St Matthew Passion a few years ago at Holy Trinity, Sloane Square and thought it a very worthwhile thing to do, even though I wondered in advance what could possibly be gained by staging so perfect - and dramatic - an oratorio? Maybe the very fact of so much drama in the music is the clue to why it worked.

Well Sir Jonathan's production was, compared with what Glyndebourne saw yesterday, entirely conventional. Katie Mitchell's production is a 'proper' staging, with characters, a controversial setting, and full-on acting. And it is also subtle, mesmerising, moving, enchanting, gripping and utterly magnificent.

Somehow she has found a way to recreate the sense of story telling and awe that the original performances of the Passion must have had. It is set in a school, "somewhere in

Europe, now", as the programme puts it. The parents have gathered after a Beslan-style tragedy. They become the audience for a retelling of the Passion story by a troupe of four travelling players. They listen, they watch, and they take part - acting as the chorus and guided through their roles by the troupe.

Parts of it were unbearably moving. There were people crying in the audience - and at Glyndebourne, that's saying something.

Benjamin Britten gave a fascinating lecture on receiving the first Aspen award, about how the way that we hear music today has changed. He cited the St Matthew Passion. Today, we can pop on a recording and there it is, in our homes. In the past, however, it was a rare and special thing to hear it - either annually at Easter or, for most listeners, perhaps once or twice in their lives. I thought of that lecture watching this near-miraculous production. Katie Mitchell and her sensationally good cast give a new sense of the wonder of how directly powerful and relevant this piece and its story can be. It wasn't a good, or even a great, performance; it felt like the Passion actually mattered to these people, and to us - even to a non-Christian such as myself.

It would be invidious to single anyone out, so I will. Mark Padmore has long been the finest Evangelist I have ever heard - and I have heard dozens of St Matthew Passions, which is, I believe, amongst the two or three greatest works of art in history. But here he was not merely a narrator but a participant, helping to heal the emotional wounds of the chorus. Mesmerising. The whole performance was spellbinding. During 'Erbarme dich', Sarah Connolly cradles a grieving father in her arms. One could not but well up.

There were, astonishingly, some boos at the curtain call. Philistinism lives on.

(UPDATE: Just to be clear, I'm not suggesting that anyone who didn't like it is a philistine - only those so rude and ignorant as to boo it!)