Secrecy came naturally to John le Carré, and there were some secrets that he fought fiercely to keep. Nowhere was this more so than in his private life. Apparently content in his marriage, the novelist conducted a string of love affairs over four decades. To keep these relationships secret, he made use of tradecraft that he had learned as a spy: code names and cover stories, cut outs, safe houses and dead letter boxes. Such affairs introduced both jeopardy and excitement into what was otherwise a quiet, ordered life. Adam Sisman's definitive biography, published in 2015, revealed much about the elusive spy-turned-novelist; yet le Carré was adamant that some subjects should remain hidden, at least during his lifetime. 'The Secret Life of John le Carre' is the story of what was left out, and offers reflections on the difficult relationship between biographer and subject.