'Of course, you've got to be ruthless' As Britain's PM for a decade and now head of his own global policy institute, Tony Blair knows a thing or two about leadership. To coincide with a new book on the subject, he reflects on the nature of decision-making, the difficulty of relinquishing power - and why a second Trump term wouldn't faze him

Were you to board an aeroplane piloted by a man who has never previously sat in a cockpit, you'd be alarmed. Were you to face surgery by a woman with no medical qualifications, you'd be frightened.

- Andrew Rawnsley

Politics is the one profession that can put someone in a position of great power and responsibility without any prior experience or demonstration of ability. "It's bizarre," Tony Blair says. "In any other walk of life, that doesn't happen." When he became prime minister in 1997 he was in his early forties and an absolute neophyte at governing. He was much better at it, he believes, towards the end of his decade at No 10 than at the outset. So he's written a book about the dos and the don'ts of leadership "because government is a science as well as an art".

In the first flush of taking power, leaders "listen eagerly" because they grasp that they know little or nothing about governing. In the second stage, they know enough to think they know everything and become impatient with listening. Hubris becomes a danger, inviting nemesis. "You've got some experience, but your experience makes you believe that you know more than you actually do. And that's the risk. That's why I say stage two is the most difficult and many people never get to stage three." Maturity comes with the realisation that what they know is not the sum total of political knowledge. Once again, "with more humility", they listen and learn. What about him? "I think I did get to stage three at the end." In his third term? "I think for the last few years. Because then I realised just how much more complicated everything was. And since leaving office, I've become much more aware of how little I know, rather than how much I know."

There is a tinge of melancholy to Blair's reflections on his time in office. He laments "you start at your most popular and least capable and end at your least popular and most capable".