With On, Off now in the book shops, McCullough has turned to Antony and Cleopatra, the final volume in her six-part Masters of Rome series. “I’m a workaholic,” she said. “I’m no sooner over one book than I have to start another. Otherwise I get bored, and everybody around me hates it. They all say: ‘I wish she’d start another book and get out of our hair!’.”