Artists, Siblings, Visionaries by Judith Mackrell review – the remarkable lives of Gwen and Augustus John

Gwen’s talent vastly outshone her brother’s – but both are treated with subtlety in this outstanding dual biographyA 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. That, we see in Judith Mackrell’s outstanding double biography of Gwen and her brother, was her ideal for living: to be at libert