Robert McNamara died this week, at the age of 93. As the US defence secretary when many of the most fateful decisions of the Vietnam war were made, he was one of the past century’s most controversial figures. He was also a successful businessman and banker.

He is fascinating now because he lived long enough to look back on his life, diagnose mistakes and draw lessons. A list of those lessons formed the backbone of The Fog of War, an Oscar-winning documentary that appeared six years ago.