I’ve just finished reading Chroma, the last book Derek Jarman wrote. He was many things: painter, film-maker, gardener, writer and activist. He was, I think, a painter first (he studied at the Slade) and Chroma is a book about colour. It’s a defiant, courageous book. It was written a year before he died of AIDS: he was ill at the time and woven into it is the day-to-day struggle he faced to save what he could of his sight. It’s an encyclopedia, crammed with facts and observations about different colours. I never knew, for example, that mauve was invented in the 19th century. He draws on a range of authorities – Aristotle, Leonardo, Newton, Kandinsky and Wittgenstein, to name but a few. One of them -I forget which- observed that the colour blue is darkness illuminated. It’s a book full of such factoids and insights, many of which stick with you.