Treachery, trust and the Tories: how Michael Gove sank Boris Johnson

I’ll buy the next round Boris, I promise. PA

From heir apparent to meek exit in one chaotic morning. After a week of post-Brexit political turmoil, former London mayor Boris Johnson’s decision not to seek the Tory leadership is arguably the biggest surprise of all.

Having led the Leave campaign in the EU referendum, the assumption was that Johnson would sweep to victory in the contest to replace David Cameron as Conservative leader and prime minister. Instead – and once again – the favourite in a Tory leadership election has failed to land the prize. In this case, he hasn’t even contested it.

How can we make sense of these developments? Two general features of leadership contests help to explain: the criteria that selectors use to choose candidates, and the rules of the selection process.

Academic research has shown that three criteria weigh heavily in party selectors’ minds when choosing a leader. First and most important, candidates must be broadly acceptable to their party and able to unite it. That is especially important when a party is clearly divided on an important issue. Divided parties rarely win elections.