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.

The spy who came in from the cold.

'The Spy Who Came in from the Cold' was the work of a wayward imagination brought to the end of its tether by political disgust and personal confusion.

Every writer knows he is spurious; every fiction writer would rather be credible than authentic.

I wrote 'The Spy Who Came in from the Cold' at the age of 30 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.

The Cold War was over long before it was officially declared dead.