Oh brother The startling lives of artists Augustus and Gwen John are laid bare in this dual biography

A young woman sits reading, a pot of tea to hand, her blue dress almost the only colour in a still, sandy room. Gwen John's painting The Convalescent shows a subdued yet happy moment, for this woman is free to think and feel.

- Jonathan Jones

That, we see in Judith Mackrell's outstanding double biography of Gwen and her brother, was her ideal for living: to be at liberty even if that meant existing in deepest solitude.

The quietness of a life spent largely alone in single rooms, reading, drawing, painting and occasionally having wild sex with the sculptor Rodin, is counterpointed in this epic narrative by the crowded, relentless, almost insanely overstimulated life of Augustus John. Lion of the arts in early 20th-century Britain, he was a bigamist, adulterer, father of so many children you lose track (so did he), and an utterly forgettable painter.