When President Trump arrives at Windsor Castle on Wednesday morning for his state visit there will be no complaints from the Conservatives, the country’s traditional center-right party. Nigel Farage, the right-wing populist leader of Reform U.K., will surely rejoice at the presence of Mr. Trump, an ally on British soil.

And although polling suggests that the U.S. president is unpopular with a majority of the British public, even Prime Minister Keir Starmer, whose center-left Labour Party is the country’s equivalent of the Democrats, is more likely to roll out the red carpet than even whisper a criticism about the president. His diplomatic strategy since Mr. Trump took office has been to woo him with praise and deference.

Of the leaders of the three parties with the highest number of lawmakers in Parliament, only one is prepared to openly criticize Mr. Trump. Ed Davey, of the centrist Liberal Democrats, will record his dissatisfaction with the president by refusing to attend a state dinner hosted on Wednesday by King Charles III.

“I personally do not think he represents the best of American values,” Mr. Davey said in a recent interview, where he accused Mr. Trump of undermining the close relationship between Britain and the United States. “He certainly doesn’t share the values that I felt have been at the base of that special relationship.”

Mr. Davey has called Mr. Trump a “bully” and a “threat to peace and prosperity.” He says the American president is the instigator of a “destructive trade war” causing economic pain for British citizens. And he accuses Mr. Trump of “betraying Ukraine,” saying: “It’s not only their sovereignty he’s selling out. It’s our security. The security of Europe and the security of our United Kingdom.”