I wrote The Spy Who Came in from the Cold at the age of thirty under intense, unshared, personal stress, and in extreme privacy. As an intelligence officer in the guise of a junior diplomat at the British Embassy in Bonn, I was a secret to my colleagues, and much of the time to myself. I had written a couple of earlier novels, necessarily under a pseudonym, and my employing service had approved them before publication. After lengthy soul-searching, they had also approved The Spy Who Came in from the Cold. To this day, I don’t know what I…