The first volume of Christopher Simon Sykes’s biography of David Hockney ended in the summer of 1975. The 38-year-old painter had just returned to Paris, where he was then living, ‘energised’ by the widespread acclaim that greeted his designs for the Glyndebourne production of Stravinsky’s The Rake’s Progress. Energy was something Hockney would need in the years ahead when the time he always wanted to devote to painting was frequently interrupted by side-projects such as stage design or an investigation into earlier painters’ use of the camera lucida, sudden passions for new technology, and the increasing demands of celebrity.