Perhaps the most celebrated writer on oil markets is Daniel Yergin. His work has won a Pulitzer and his advice sought by every president from Bill Clinton to Donald Trump. Let’s start by looking at an example.

Fifteen years ago, before the US and Israel started their war on Iran, killing thousands of civilians in the process, before the strait of Hormuz became as infamous as the Bermuda Triangle, and before experts declared “the greatest global energy security threat in history”, Yergin published The Quest: Energy, Security and the Remaking of the Modern World. After hearing Trump announce a “very soon” end to the conflict for the second – or was it the third? – time, I dug out my copy. Just as I remembered, it devotes a chapter to the Persian Gulf.

As far back as 2011, Yergin was anxious about the strait of Hormuz, which he calls “the number one choke point for global oil supplies”. Both oil buyers and oil sellers know how swiftly Iran could shut this narrow thoroughfare. A general in Tehran warns: “Enemies know that we are easily able to block the strait for an unlimited period.” Even before the spread of drones, the Islamic Revolutionary Guard Corps had the firepower to reconfigure Gulf geography. A leader of an Arab Emirate calculates his country is only “46 seconds from Iran as measured by the flight time of a ballistic missile”.

I do not offer this passage as some great feat of prediction, but quite the opposite. Yergin was simply putting together what was threatened in public, known to diligent observers and produced in government war games: use military force on Tehran and it will respond by inflicting economic agony. That simple truth was glaringly obvious, yet still Trump ignored it. The past month can be summarised as a big orange man steps on a rake – and wonders how he got a black eye.

But now Washington’s supreme leader has provoked the chokehold of 20% of global oil supplies, the rest of the world will suffer the........

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