During the long period of the cold war, which lasted for more than four decades after the end of the second world war, nothing infuriated me more than the question often put to me: “Is there going to be another world war?”

It was obviously even more unpleasant to contemplate than any kind of economic setback. But it seemed to me a pointless and unproductive kind of discussion. I could have answered “a 10 per cent chance”, “a 50 per cent chance”, or “an 80 per cent chance” with equal plausibility. I did not and could not know. Nor could anyone else. This kind of pointless crystal ball-gazing only deflected attention from a much more important question. This was: “Are we doing enough to reduce the probability of such a catastrophe?” By “we” I did not mean mankind in general but the government of the country in which I happened to live and was a citizen, namely the UK.