Years ago, when I was a diplomatic correspondent, I had a list of infallible sources. These weren’t people I ever spoke to—but their judgment was reliably unsound.

If the US politician Robert S McNamara believed in anything, I found it fruitful to believe the opposite. Poor Mr McNamara (the S was for Strange) spent a lifetime of high achievement getting everything wrong. As an adviser to John Kennedy he discovered the “missile gap,” which led to huge and needless investment in nuclear weapons; as secretary of defence he doggedly pursued a hopeless war in Vietnam; and later, in the 1980s, he espoused “no first use” of nuclear weapons in Europe when nuclear weapons were NATO’s sole credible form of defence. He died garlanded with honours.

Another favourite of those years was Hans-Dietrich Genscher, the long time German foreign minister. If he believed that the leaders of East Germany deserved red carpet treatment you could safely bet that they were about to be run out of town by their own people. The German-British sociologist and politician Ralf Dahrendorf had an honourable position among my antiheroes, for reasons too lengthy to explore here. So did …