The merit of The Spy Who Came in from the Cold, then – or its offence, depending where you stood – was not that it was authentic, but that it was credible.

John LeCarre, explaining that he didn't have insider information about the intelligence community, and if he had, he would not have been allowed to publish The Spy Who Came in from the Cold, but that a great many people who thought James Bond was too implausible wanted to believe that LeCarre's book was the real deal.