The first-ever summit of G20 leaders was held in Washington in late 2008. Although US credibility had been hit by the collapse of Lehman Brothers and the Iraq war, there was no doubt that the most important leader in the room was the host — President George W Bush.

Nine years later, as the G20 prepares to meet in Germany, it is no longer clear that the rest of the world can look to the US president for leadership. Donald Trump’s slogan is “America First”. Meanwhile, other aspirants to global leadership are stepping forward. Xi Jinping, the president of China, is clearly positioning himself as the defender of forms of international co-operation rejected by Mr Trump. And although Angela Merkel has rejected the idea that she is the leader of the west as “grotesque”, the German chancellor is becoming increasingly outspoken on global issues.

If it was up to the citizens of the world, it seems that Ms Merkel would get the job of global leader. A Pew poll published last week showed that in a cross-section of 37 countries, 42 per cent expressed confidence in the German chancellor to “do the right thing” — compared with 28 per cent for Mr Xi and just 22 per cent for Mr Trump.