Charisma is, as Max Weber famously argued, a critical element of political leadership despite the fact that it is almost impossible to measure, define or quantify. The simple fact is that – like him or loathe him – Boris Johnson is charismatic. I remember watching him address a large public audience in Bromley during the summer of 2010 as part of the Mayor of London’s ‘Outreach’ initiative. What was immediately striking was the manner in which he captivated the audience. They were entranced to the extent that strident political opponents seem disarmed by his rhetoric, energy, and emotion. He knew how to play the audience like a conductor on a podium, and play them he did. Yet, charisma on its own is not enough, and just as Machiavelli argued that a true leader needed the strength of a lion and the cunning of a fox, so too must charisma be matched by guile.