The cold war provided the perfect excuse for Western governments to plunder and exploit the Third World in the name of freedom; to rig its elections, bribe its politicians, appoint its tyrants and, by every sophisticated means of persuasion and interference, stunt the emergence of young democracies in the name of democracy.

But I think the real tension lies in the relationship between what you might call the pursuer and his quarry, whether it's the writer or the spy.

In itself, the practice of deception is not particularly exacting; it is a matter of experience, of professional expertise, it is a facility most of us can acquire.

During the Cold War, we lived in coded times when it wasn't easy and there were shades of grey and ambiguity.

It's part of a writer's profession, as it's part of a spy's profession, to prey on the community to which he's attached, to take away information - often in secret - and to translate that into intelligence for his masters, whether it's his readership or his spy masters. And I think that both professions are perhaps rather lonely.

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. Fifty years on, I don't associate the book with anything that ever happened to me, save for one wordless encounter at London airport when a worn-out, middle-aged military kind of man in a stained raincoat slammed a handful of mixed foreign change on to the bar and in gritty Irish accents ordered himself as much Scotch as it would buy. In that moment, Alec Leamas was born. Or so my memory, not always a reliable informant, tells me.

I don't think it is given to any of us to be impertinent to great religions with impunity.