The last time a US president visited the UK at Christmas, it was in a Richard Curtis film and Hugh Grant was the prime minister. This week, real-life Hugh Grant has been knocking on doors with Lib Dem and Labour candidates urgently trying to stop Brexit, and the guy who demanded a cameo in the film Home Alone 2 has been the “leader of the free world” for three years.

Back then, people called the Curtis film – Love, Actually – smug. But in retrospect, it had nothing on the west.

Only a wildly misplaced sense of self-satisfaction could possibly have got us where we are today. Which is to say, watching a Wotsit wearing a four-foot red tie give a press conference in the US ambassador’s London residence, during which he reduces Nato’s complex geopolitics to the level of suburban real-estate rivalries. As a visitor, Trump has a strong Ghost of Christmas Future energy to him.

Those who love clinical narcissists – and who doesn’t? – will be disappointed that Trump and Boris Johnson will not be doing a joint press conference at this Nato summit. But it is believed the crossing of their two streams would have had the potential to rip the very fabric of reality, creating a reversal of Nato’s original aims, and plunging the 70-year-old alliance into immediate land war with Russia.

Also there’s an election on, and the Tories sense even a handshake with Trump could piss their electoral bed.

So there won’t be the chance to press the PM on the time he turned his Quick-Quotes Quill on Donald, accusing him of “a quite stupefying ignorance that makes him, frankly, unfit to hold the office of president of the United States”. Trump is just clever enough to pretend this never happened, which is always a neat way of insulting an overpromoted journalist. (Orson Welles used to greet the critic who gave him his worst reviews effusively every time he saw him, “so he would think that I’d never read a word he wrote”.)

Indeed, Trump used his impromptu press conference to stress his blissful unfamiliarity with a great number of things. Appearance-wise, the US president’s lips are a sort of pouting anus – a mouth sphincter which today emitted a roll-call of guys and stuff he didn’t know.

Take Prince Andrew. “I don’t know Prince Andrew,” Trump sighed with a moue, despite there being significant photographic evidence to the contrary. “But it’s a tough story. But I don’t know him.”

Or take Labour’s leader, Jeremy Corbyn. “I know nothing about the gentleman,” Trump shrugged, having very recently described the Labour leader as “so bad for your country”, warning he’d “take you in such a bad way”. None of that today. “Really. I know nothing about him,” he said.

Or take the notion that Trump thought the NHS was on the table in a future trade deal between the UK and US. “I don’t even know where that rumour started,” mused the president, who used his state visit in June to tell the massed TV cameras, “When you’re dealing in trade, everything is on the table.”

Today the president was pushing a line that sounded distinctly like it had been crayoned on to giant cue cards held aloft by the Conservative campaign team. “We have absolutely nothing to do with it,” he insisted of the health service, “and we wouldn’t want to if you handed it to us on a silver platter.”

Alas, Trump delivered this with the same wooden conviction with which he addressed Macaulay Culkin in Home Alone 2, when he was asked where the Plaza hotel lobby was. “Down the hall and to the left,” gurned Trump, in a manner to make you think it was upstairs and to the right. And so with his NHS speechlet, during which he felt convincingly out-acted by the ambassador’s furniture.

Still, I hope Trump welcomed the chance to visit the originals of the faux-antique armchairs that litter his properties. His state visit in June featured a trip to Westminster, where his reaction to being shown a slab commemorating Lord Byron was to ask what type of marble it was, perhaps with a view to getting it as a shower tray or something.

Even Trump’s memories are ersatz reproductions of events. “You know that I was a fan of Brexit,” he reminded journalists. “I called it the day before. I was opening up Turnberry.” In fact, he opened Turnberry the day after the Brexit result, when even that great seer David Cameron was beginning to get a bad feeling.

As for the rest of the president’s plans for the day, they seemed to have involved giving Emmanuel Macron a wedgie and preparing for tonight’s Buckingham Palace reception with the Queen. The best way to do that was with some hardcore fundraising, and he was reported to be offering London-based US business people a chance to attend a reception with the president for $35,000, a photo and the reception for $50,000, and $125,00 to join a roundtable.

Bigger spenders shouldn’t fret – there’s bound to be a secret price list for the guys who want to pay even more for something really special. Namely, the ambassador gig in a former breakaway Soviet republic, and the chance to hole up in one of the boutique Federal Correctional Institutions when you get out of your depth.

So doubtless a good day was had by all. Well, all except one, perhaps. Over on a FiveLive phone in, a certain close friend was acting totally, totally, cool about not having a meeting lined up with the president.

“I have not, no,” blustered Nigel Farage. How come? “Well, this is a bit awkward, isn’t it? Whilst he’s a friend of mine, there’s a general election going on, so I don’t intend to …” How about a quick WhatsApp? “If there are some personal exchanges they would be purely personal. I wouldn’t talk about them.” You wouldn’t shut up about them, dear. Commiserations today and for next week. I’m sure he’ll remember you fondly.