U.S. President Donald Trump got the pomp and ceremony of a three-day state visit to the United Kingdom that he so craved, a perfect televisual boost to his upcoming re-election campaign. Departing Prime Minister Theresa May got one final shot at international relevance, having none left domestically, by welcoming the U.S. leader before retreating into well-earned obscurity. The House of Windsor, led by a faintly amused-looking monarch surrounded by most of her extended family, allowed itself to be played into the purposes of a visiting foreign dynasty.

The queen’s amused demeanor reflected, inter alia, that re-election is not, and never has been, one of her worries. Mr. Trump quickly chose to wade into internal politics, not only of the country but also of the Tory Party, appearing to relish the unconventional role of kingmaker that he had found himself occupying, an unexpected bonus addition to his usual tendency to make everything about himself.

Tory candidates to succeed Mrs. May were confused about how much good any praise from the American president might do them. Mr. Trump randomly namechecked some of them and ignored others, praising Boris Johnson. An unexpected newsline popped up as Mr. Trump suggested that the cherished N.H.S. (National Health Service) would be “on the table” in any post-Brexit U.K.-U.S. trade deal—a position he was soon required to walk back. Other than that unexpected morsel, Mr. Trump broadly stuck to the script at carefully choreographed diplomatic moments, even as some potential controversy seem to lurk around just about every corner.

Even before he touched down, the president managed to spike anxiety levels as news media spotted the president tweeting from Air Force One while on approach into London’s Stansted Airport. You and I, ordinary passengers, are always firmly told to leave our phones in airplane mode until the aircraft has reached the taxiway, but when you have got the nuclear codes in a hold-all above you in the overhead compartment, those rules are trivialities.

Even before he touched down, the president managed to spike anxiety levels as news media spotted the president tweeting from Air Force One.

The target of his airborne assault tweet was London’s popular mayor, Sadiq Khan, a politician Mr. Trump has been trying to pick a fight with for some time. According to the president, Mr. Sadiq is a “stone-cold loser” who has done a “terrible job” as mayor; the only near-specific adduced of his terribleness was an inaccurate comment about municipal crime.

While street violence, particularly among the young, is a worrying feature of London today, many political analysts here are certain that it was the austerity policies of Mr. Trump’s Tory friends, not least reducing police numbers by over 20,000, that created the problem, not the Labour Party mayor. More disappointingly, in the same tweet was the president’s rude remark about Mr. Khan’s height—he’s a short, wiry man—here compared to another Trump object of animus, the tall Mayor Bill de Blasio of New York, with whom Mr. Sadiq has worked closely. And all this before the wheels touched the Essex airport’s tarmac.

Protest against Mr. Trump’s visit—specifically that he had been honored with a full-blown state visit—was loud and visible on London’s streets although organizers conceded that the numbers fell below expectations and were below the huge numbers of protesters during his previous, non-state visit. The famous Trump baby blimp flew again over Parliament Square. The president blatantly lied about the protests, claiming that there had been a big turnout of Brits demonstrating support and even “love” for him and that the “fake news media” had, of course, found some protestors to write about, but they were not really there because he had not seen them.

Not everyone in this proudly multicultural and diverse city is prepared to ignore the president’s misogyny, Islamophobia or racism; many see in him the catalyst for the normalization of such attitudes in the United Kingdom and elsewhere. Others, mainly Tories, droned on about respecting the office of the president, wheeling out, of course, the “special relationship” trope, one that has always had much more meaning, if often expressed with a tinge of desperation, on this side of the Atlantic.

Some of us still wonder: What was this state visit’s purpose? Mr. Trump is only the third U.S. president to be granted such an honor; the prime minister, days away from quitting Number 10, was the lamest of ducks, so there was no pressing diplomatic justification. One need not share this correspondent’s disdain for the unelected hereditary monarchy to regret the poor political choice that forced a woman prime minister to make nice with such a man, one entirely lacking any respect for women.

Apparently part of the justification for the pomp and circumstance in London was to get Mr. Trump to the beaches of Normandy where dramatic and moving ceremonies took place to mark the 75th anniversary of the D-Day landings; but he could have attended those events without the state visit tagged on.

The presence of the dwindling numbers of D-Day veterans, heroes all, upstaged him anyway. In any case Mr. Trump failed to stay for the entire commemorative program, nipping across to County Clare in the Irish Republic to play a round of golf at one of his resorts. (While there he managed, if only for a moment, to mystify the Republic’s Prime Minister Leo Varadkar by suggesting that the Republic’s post-Brexit border with Northern Ireland could be compared to his proposed wall on the Mexican border.)

But there was perhaps more going on during this visit than just the soothing of one elderly man’s gigantic ego. A huge clue came during the previous weekend’s political TV shows, when the U.S. ambassador, one Woody Johnson, made it clear that the U.K.’s National Health Service would be “on the table” in post-Brexit trade talks between Britain and the United States that are already slated to be held.

Mr. Trump confirmed this ambition—although later appeared to contradict himself—in a joint presser with the prime minister, when he had to turn to her to ask what the abbreviation N.H.S. meant. Perhaps in the near term we should watch for a slew of privatizations as the sell-off of the Health Service swings into action. Watch how the big insurance companies begin to circle their prey, knowing that a compliant right-wing government will smooth their way. Watch for the strangulation and asphyxiation of this most cherished institution here and then remember this otherwise pointless state visit.

Correction June 10, 2019; 4:21 p.m. EDT: The last name of ambassador Robert Wood Johnson was misspelled as Johnston.

David Stewart, S.J., who was the London correspondent for America from 2014 to 2020, files from his native Scotland, where he now lives and works.