It has taken talent scouts many years to discover me. But finally the long-awaited invitation from the BBC Symphony Orchestra drops into my e-mail inbox: “Do you fancy making your piano debut at the Barbican?” Indeed I do. I can deny my public no longer. I picture a concert hall packed with screaming young women, hurling their knickers at me. Then I read on, and discover that my debut will involve playing just three bars of Erik Satie, very, very slowly, 15 times in a row, for 20 minutes, as part of an 18-hour piano marathon.

The news that Yoko Ono and Matt Goss, formerly of Bros, will be taking part cheers me a little. And the news, shortly afterwards, that Goss has pulled out — because the music is too difficult to read — cheers me even more. This is no assignment for sun-dried lightweights. Then I look at the music and begin to sweat.

Nobody is quite sure whether Erik Satie meant Vexations — a theme and two harmonic variations repeated 840 times — as a deadly serious piece of conceptual art or a seriously deadly musical joke. Although the piece is not technically difficult, Goss was right: it is very difficult to read on the page.

By the 6pm start, the Barbican conservatory is packed. Beaming, Richard Sisson (of cabaret duo Kit and the Widow) sits at the piano. And we’re off. Ninety seconds later, a woman draws a large red “1” on a flip chart. There’s a ripple of laughter. Sisson continues, a little quieter now.

By the time the third stripe is marked up on the board, the chuckling has ceased. Even Sisson isn’t looking quite so cheerful. He’s staring fixedly at the music, as if it has just stolen his parking space. Gradually, however, the piece begins to weave its subtle spell.

“Now I’ve done it, I want to do it again,” Sisson tells me later. “The less meretricious it is, the better. I’m afraid the way I played it was positively tarty.” This, it turns out, will be the key distinction between the 50-odd pianists who attack Vexations over the next 16 hours: between those refined souls who can submerge themselves in the music’s monotony and the tarts who can’t resist trying to make it sound interesting.

Next up, the composer Michael Berkeley emerges looking wild-eyed. “You’d go mad without a little variation,” he pants, knowing that he, too, has been guilty of rank tartiness. Even Alan Rusbridger, editor of The Guardian, is not immune: “When I was practising, I played it straight. But after a while, boredom or individuality sets in.”

Then it’s almost midnight, and my big moment approaches. The room is packed. And my hands are shaking. “Am I pleased to see you,” murmurs Roger Wright, controller of Radio 3, as I slide onto the piano stool beside him. “You’re in the wrong career,” I whisper, annoyed at how well he can play. “I know,” he says. “I should have been a cricketer.”

Then he’s on his way, and my trembling left hand is playing the first three notes of the theme. People have told me that I will forget about the audience, that I will lose myself in the music. But as my first stripe goes up on the flip chart, the attention-seeking artiste in me takes over. Sisson may think his playing was tarty, but I give it the full slapper. If he evoked Mata Hari, I am channelling Jordan.

I experiment with emphasising the various voices of Satie’s harmonisations in turn. I adopt an extreme, overlapping legato. I even have a go at holding down the sustain pedal for an entire blurred rendition. I truly am beginning to lose myself in the music. It’s just not quite the music that Satie intended. Now we’re rattling along nicely. I even make a few forays into staccato territory, feeling a faint shuddering through the pedals that is presum-ably Satie turning in his grave.

All too soon, a smiling dude in a hip hat sits down beside me, and serious jazzer Django Bates is taking over. Reluctantly, I yield to him and lose myself in the crowd, feeling strangely naked without the fig leaf of the audience’s applause (let alone their knickers). “Well done, Michael,” says a friend. “Very ... unusual.”

The whole experience has been unusual, and magical, too. It has all been anything but vexatious. Though I fear the gap between my debut and my comeback performance will be a very long one.