Britain is the motherland of eccentricity – Cambridge’s May Week in June, elections on Thursdays, carpeted bathrooms and the Duke of Devonshire’s seat in Derbyshire. But surely among the oddest quirks is the way the Conservative party goes about choosing a new leader. In what is a gift to its opponents, the candidates spend months publicly tearing into erstwhile colleagues, as if they were from opposing parties, to win over party members.