Jonny Greenwood on BBC Radio 4

Jonny Greenwood tells BBC Radio 4's The Film Programme, at Abbey Road, that the music over the first 12 minutes of There Will Be Blood was never written for a film. It was a Radio 3 commission for the BBC Concert Orchestra, and Paul Thomas Anderson first heard it on a fan's bootleg. It came from long drives as a child, when a cassette was played until everyone was sick of it, and after it went off he pretended he could still hear the song in the engine noise. He wanted it to work as an 808 drum machine made out of orchestral white noise, and it failed, because an orchestra isn't accurate enough; even a block chord of white noise can't be done, since everyone would have to play a different frequency at exactly the same volume. The mistakes, notes poking out of the wall of sound, are what he loves in it. “Our brains often fill in music that isn't there,” he says, like the radio a person still hears when the vacuum cleaner stops.

He is against recording orchestral music in general and thinks it has to be seen, which he admits sounds like a cheesy plug for the concert: There Will Be Blood plays Meltdown, at the Southbank Centre in London, on 19 August, with an orchestra playing his score live under the film. When the film was screened with the score played live at the Roundhouse in London, a pillar was often in his way, and the orchestra agreed not to watch the film, except at the dress rehearsal, with Daniel Day-Lewis's enormous head looming over them. Most film scores are “disturbingly good” once anyone pays attention; Michael Clayton, which he saw the other day, has a score that slips by until a second watch with an ear on the music. A Bond film or a hundred-million-dollar romantic comedy does not tempt him. The bigger the film, the more control passes from the director to people higher up, and working with Lynne Ramsay and Anderson has been genuine fun all the way through.