n Artists, Siblings, Visionaries, acclaimed biographer Judith Mackrell turns her attention to British brother and sister artists Gwen and Augustus John.

In many ways they were polar opposites.

Augustus was the larger of the two; vivid, volatile and promiscuous, he was a hero among romantics and bohemians, celebrated as one of the great British talents of his generation.

As a woman, Gwen's place in the art world was much smaller, and her private way of working and reserved nature meant it was only long after her death that her tremendous gifts were fully acknowledged. But her temperament was as turbulent as her brother's. She formed passionate attachments to men and woman, including a long affair with the sculptor Rodin.

And there were other ways in which the two Johns were remarkably alike, as Mackrell vividly reveals. The result is a powerful portrait of two prodigiously talented artists and visionaries, whose experiments with form and colour created some of the most memorable work of the early twentieth century.