I have known Elon Musk for more than a decade.

We have exchanged ideas, drunk whisky together, met one another's children, and debated everything from the war in Ukraine to the future of American education.

I have long said he is the Napoleon Bonaparte of our times. Walter Isaacson's new biography, based on two years of shadowing Musk, reaches a similar conclusion.

And at a time when the richest man in the world is being transformed in some quarters from hero to villain, this historical analogy should not be ignored.

In 2017, Musk and I went for a drink in California's Menlo Park with one of my sons, then 18 and about to embark on a gap year in Africa.

Musk was preoccupied. Halfway through our conversation he took a video call from one of his Tesla factories, which appeared to be on fire. 'Is it important?' he asked. The guy in the burning factory seemed unsure. 'Then don't bother me,' he snapped and hung up.

'Don't go to South Africa,' he said to my son, with sudden intensity. 'You'll die.' My son disregarded this advice. A few months later he narrowly avoided being shot during a carjacking in Johannesburg.