You’ll have heard of perfect pitch. Well, Derek has absolute pitch — a rare gift, meaning that, when he hears a chord with ten notes in it, he can identify every one. Most professional musicians can get about five.

He can master any melody on earth, has a databank of thousands of songs in his head and can play any one of them at will, improvising as he goes.

One member of the audience asks him to play Ain’t No Sunshine. Another suggests that he play it in B major. And another, that it’s done in ragtime. No problem — without a pause, his fingers flutter across the keyboard in a hummingbird blur of staggering virtuosity…

What had happened? How had he magically summoned up the capacity to produce music from within his damaged brain? ‘His fascination with abstract patterns of sound, those thousands of hours spent simply listening during the first 20 months of his life, largely uncontaminated by understanding, had caused millions of special neuronal connections to form,’ says Professor Ockelford. ‘And it was those connections that now lay behind the emergence of a precocious musicality.’