America’s culture wars came to London last week. Donald Trump likes to bring disruption with him. During his state visit, he also brought his extraordinary ability to drive his opponents to physical violence.

Anti-Trump mobs, modeled on their American equivalents, whipped themselves into what can only be called an ecstasy of odium. “No to hate!” they chanted, their faces contorted with hate. “No to intolerance!” they added, hurling milkshakes at people they imagined might not share their views.

Footage showed an elderly man being set upon and wrestled to the ground because he was wearing a red cap. Yes, comrades: That’ll show the bigots!

I wish I could write that the demonstrators were a tiny leftist fringe, but the truth is that this kind of tribal violence is becoming more and more mainstream. People are increasingly likely to define themselves by the people they dislike, to prefer grievances to solutions, to disbelieve anything that doesn’t come from “their” news media, to elevate street protests over democratic elections.

Jeremy Corbyn, the Labour leader, made a virtue out of not meeting Trump. He is happy to meet the leaders of Cuba, Venezuela, Hamas, the Irish Republican Army, and Hezbollah, but not the leader of the free world. Supposedly moderate Labour figures recorded anti-Trump videos, even as the veterans gathered, probably for the last time, to celebrate the Normandy landings.

There was a time when that anniversary would have been enough to make politicians act like adults. The United Kingdom is free partly because a previous U.S. president ordered his troops to stand by us in our need. The English-speaking democracies then went on to liberate hundreds of millions of people from tyranny. That alone would recently have been enough to ensure that any U.S. president was welcome in Britain.

Now, though, the Labour leader is to be found speaking at anti-Trump rallies while his members of Parliament dismiss the President’s supporters as fascists — seemingly oblivious to the irony in making this idiotic claim even as their nation honors those who fought against actual fascists.

The funny thing is that, on this occasion, Trump comported himself in a way that was almost statesmanlike. His tribute to the queen and the Anglo-American alliance was beautifully judged. His solecisms were relatively few. He made only one real gaffe. Asked at a press conference whether a U.S.-U.K. trade deal would include everything, even the National Health Service, he said that, yes, it would all be on the table.

My sense is that he was trying to be helpful by making the point that the trade deal would be as comprehensive as possible. I’m not sure he knew what the National Health Service was. He certainly can’t have had any idea of how people would leap to the defense of Britain’s hallowed, albeit underperforming, healthcare system.

British leftists are never happier than when claiming that their enemies plan to “privatize the NHS." They never specify what they mean by that claim. Even they surely can’t imagine that a government would sell shares in the National Health Service, or that investors would be mad enough to buy them.

No, what they are doing is cynically conflating two quite separate things: the moderate internal market introduced by former British Prime Minister Tony Blair, which allowed for more contracting out of services; and the idea that Britain might somehow — no one ever tries to explain how — adopt a U.S.-style healthcare system, in which treatment is no longer free at the point of delivery. It goes without saying, although Trump made a point of spelling it out the following day, that a trade deal cannot determine how a country finances its healthcare system.

The only thing that a free trade area might affect is the freedom to bid for things that are already being contracted out. When the National Health Service buys in a service, say, cleaning or agency nurses, British and EU firms are guaranteed the right to offer their tenders. A free trade area might allow British and American service providers to bid for contracts on each other’s territories.

Can anyone seriously object to that idea? Is anyone prepared to stand up and say that it’s fine for a French or German company to win a contract but that an American one should be excluded solely on grounds of nationality? Because that’s the only concrete thing that people mean when they say, "We must protect our beloved NHS from Donald Trump’s corporate cronies."

Not that it’s really about the National Health Service at all, really. Or about Muslims or Mexicans or minorities. It’s about visibly having the right enemies, about hating Trump more ostentatiously than the protester next to you. How small we can be.