Boris Johnson is becoming the Where’s Wally? of international diplomacy. All over the world the geopolitical tectonic plates are shifting yet at this time of huge global significance the foreign secretary is all but invisible on the international stage. On the nuclear threat posed by North Korea, the crisis over Saudi Arabia and Qatar or the clash between the US and China, he is irrelevant. On Syria, Afghanistan, Iraq, Iran, Russia, Venezuela, Turkey and Yemen, he is incoherent. Occasionally he surfaces briefly, like a hostage paraded before the television cameras to prove he is still alive, as he did after a visit to Libya last week, but even then he is ineffective because he has ceded all influence to others.

As the US enters an