Like him or loathe him, there is no denying Keir Starmer has his work cut out negotiating that bundle of contradictions which is Donald Trump.
How should he deal with a US president who can post something incendiary before going to bed, only to change his mind by breakfast?
Mr Trump’s latest off-the-cuff remarks to reporters are just another in a long line of bizarre utterances. He claimed Iran wanted to make a deal to end the war, but when pressed on who he was talking to said they were dead.
The president was alarmed by a social media video showing the US aircraft carrier Abraham Lincoln under attack and on fire. His military chiefs had to tell him it was a fake. But it's a worry if random social media is where the most powerful man on earth gets his information.
Mr Trump seemed surprised that Keir Starmer needed to talk to his ministers before making any decision on sending British warships to the Strait of Hormuz.
Mr Trump told him: “Why do you have to meet with your team to find out whether or not you send some minesweepers to us?”
Because, Mr President, the UK is not a dictatorship and the prime minister governs with a Cabinet. He may be first among equals, but it would be extraordinary if he did not consult the other equals before putting British lives in danger.
And what’s all this with the Royal Navy getting involved anyway? It was only eight days ago that Mr Trump said there was no point in our ships turning up late, given the war was won. I have an inkling of what Keir Starmer must feel like, having worked for Robert Maxwell.
There are a lot of similarities between the monstrous tycoon and the president. Both are physically big men with big personalities who could dominate even the most crowded room.
Both mercurial and unpredictable, and likely to switch direction without warning. Both are lacking in intellect but nevertheless skilled and instinctive streetfighters in business and politics.
Donald Trump and Robert Maxwell are two sides of the same coin - Nigel Nelson | Getty Images
Mr Trump is a convicted felon. Robert Maxwell would have become one had he lived long enough to be convicted of stealing £450million from Mirror Group Newspapers' pension funds.
Both tend towards tyranny and grand gestures and terrifying those around them, yet are also figures of fun. We laughed at Maxwell behind his back, much as US comedians make hay poking fun at the president to his face.
Maxwell bought himself a private helicopter and installed a helipad on the roof of the Mirror's skyscraper headquarters in London’s Holborn.
Before taking off, he would pee over the side of the building. Anyone below who thought they had detected a drop of rain was experiencing something far more unpleasant.
He fired me once for disagreeing with his interpretation of Parliamentary privilege, which he didn’t understand, even though he had been an MP. Like the US president, his opinion did not invite dissent.
Being sacked was not a surprise – a lot of people were. It was being rehired two minutes later in the same conversation, which took me aback.
I never did fathom why, but having felt the wind from Maxwell's bullet, I wasn’t about to ask. Out of the blue, Maxwell decided what Northern Ireland needed was a military governor.
This was madness. Along with Alastair Campbell, who worked for the Mirror before becoming Tony Blair’s right-hand man, we tried to talk him out of it.
Of course, we failed. But Maxwell forgot about it, which he was prone to do. Just as President Trump seems to have forgotten about taking Greenland.
The president's threat towards the future of Nato if Europe doesn't stump up in the Strait of Hormuz is completely irrational. There is no link between one and the other.
As former Chief of the Defence Staff Sir Nick Carter told the BBC: “Nato was created as a defensive alliance.
"It was not an alliance that was designed for one of the allies to go to war of choice and then oblige everybody else to follow.
"That’s not the sort of Nato any of us wanted to belong."
Loyal MAGA fans will nod along with their hero, whatever he does. The rest of us might reflect on whether upending the global order really is in the world’s best interests.
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