In May 2002, the free jazz pianist Cecil Taylor performed at the Barbican with the post-minimalist classical ensemble Bang on a Can All-Stars. I managed to slip backstage during the rehearsal. It was tense. Taylor, wearing a dressing gown and pink fluffy slippers, was in the process of firing half the ensemble. Bang on a Can’s keyboard player had already gone, and a procession of other players would soon follow. Their sin seemed to have been to read Taylor’s graphic sketch for how the evening’s music might evolve too literally. With the concert itself underway, Taylor ritualistically shredded his sketch and encouraged the remaining Bang on a Can musicians to do the same: they were going to have to improvise. A hapless guitarist threw a rock riff at Taylor, which he immediately bounced back as an open-ended question: is that the best you can do? Then he turned his back on the ensemble and carved out a cavernous wall of sound with his own drummer, Tony Oxley.