Oh, for an American Macron! Why isn’t it possible in the US for a presidential candidate to leave his or her party and run as the representative of a new movement, and win? Why can’t Americans just reshuffle their political landscape and build a new majority?

We know the answer. France has a parliamentary system with a strong president, whereas the US’s winner-takes-all elections and single member districts tie it to the two-party system forever. This widespread view is known in political science as Duverger’s law. It holds that multiple parties are far more likely where proportional representation operates. But under first-past-the-post, a vote for a third party is wasted.

So while the same underlying dynamics shaped the American and French presidential elections — radical disaffection with traditional parties and the status quo — they led to dramatically different results. In France the traditional party candidates were knocked out in the first round, leaving the far-right and a standard bearer for a new movement, who then won. In the US, Bernie Sanders and Donald Trump were the anti-establishment candidates. Mr Sanders provided serious competition to Hillary Clinton, the establishment candidate on the left, but lost to her.