THERE REALLY SHOULD be a German word for it – maybe there is: when you know something should shock you, but it just doesn’t anymore. You’ve become desensitised. In politics, this feeling has become increasingly familiar. Over the past few years, all that was thought solid has melted into air – hot air in most cases. 

The first sign of serious political climate change arrived in June 2016 when a majority of Britons voted for Brexit, giving the proverbial two-fingered salute to almost the entire British political class. This was a huge surprise from which British politics is arguably yet to recover. But when later that year in the US presidential elections Donald Trump, a boorish, self-aggrandising businessman with a penchant for lying, defeated Hillary Clinton, doyenne of the American political establishment, the shockwave that rippled through newsrooms and political-science departments could have triggered seismometers. Hardly anyone predicted the outcome, but there it was. Decades of political convention were upended.