In the two most populous nations of the English-speaking world, political leadership has reached a crisis. Large sections of President Donald Trump’s own Republican Party in the United States are in open rebellion following his “sell-out” summit conference with Russia’s Vladimir Putin. In the United Kingdom, the Conservative Party is showing every sign of splitting into warring factions in response to Theresa May’s complex formula for the UK’s future relationship with the European Union – also labelled by her critics as a “sell-out”.