Jonny Greenwood on BBC Radio 4

John Wilson visits Jonny Greenwood's music room in the Oxfordshire countryside for the Today programme, the day before his Proms debut as a composer. He shows off a tanpura he will play, with terrible tuning, one of dozens of instruments in the room. The late-night Prom he has curated puts Steve Reich and Penderecki beside the premiere of his own piece for 68 strings, seven movements in a handwritten score. Each movement copies a different way of faking reverb, one of them an 80s digital delay unit Joy Division's producers loved, which can shift every echo up or down a few semitones so the sound cascades.

“It's horribly self-referential,” he says, but he always feels he is writing music about the instruments themselves, here the violin he grew up learning. The first rehearsal is always a sweaty 20 minutes of ticking and crossing out, the day before the premiere, like a firework display.

The biggest moment of his musical life was a plastic recorder at five or six, and he still plays it all the time. He owes everything to the peripatetic teachers Oxfordshire County Council sent to his primary school, and it upsets him to see music treated as a luxury or a hobby.