“This was almost like a last resort by a kind of spokesperson or a respected figure of the international community to walk into the beehive without getting stung and to say what needs to be said once and for all,” he added.

Unlike his mother, Queen Elizabeth II, whose near-universal popularity defined an era, Charles has had a more uneven public reception over decades as heir and since his ascension to the throne in 2022.

But parts of the British press, long critical of the monarchy’s handling of Mountbatten-Windsor, have rallied behind Charles in recent days, casting his trip to the U.S. as a moment that assured his position as a ceremonial but not political leader.

Britain’s powerful and conservative Daily Mail newspaper said the king delivered a “diplomatic masterclass” during his speech to Congress on Tuesday, where he wrapped appeals to history and shared values in disarming humor, cracking jokes about Britain’s past while pointedly stressing the need for alliances and support for Ukraine.

The same day, the left-leaning Guardian and right-wing Daily Telegraph newspapers also splashed images on their front pages of Charles at the congressional dais. The Daily Mirror featured an image of Charles and Trump laughing together, calling the king’s speech to Congress “historic.”

Later on Tuesday at a state dinner, Charles broadened his remarks beyond the alliance to constitutional and environmental themes. He included references to executive power being “subject to checks and balances,” delivered amid a war not approved by Congress, and to “the disastrously melting ice caps of the Arctic.” Trump, his host, is a climate change skeptic.

And against a backdrop of American-British relations arguably at their lowest point in decades — strained by the Iran war, Trump’s disagreements with NATO and his criticism of Britain’s immigration policies — Charles, whose distant ancestor King George III lost the American colonies 250 years ago, now represents a symbol of continuity in the relationship between the U.S. and the U.K., another analyst told NBC News.

King Charles III has become a “very skillful diplomat and a real asset” to the U.K., said Jamie Gaskarth, a professor of foreign policy and international relations at the Open University.

“I think he is able to kind of express these things in a way that Prime Minister Keir Starmer isn’t,” he added. “His speeches actually were surprisingly frank and pointed in some respects.”

Andrew Barclay, a politics lecturer at the University of Sheffield, said the king is able to say things that heads of government can’t because he doesn’t set policy.

While Trump swings from being “charming and effusive to being very bad-tempered with Starmer and other European leaders, usually getting specific policy commitments out of them,” Barclay said, the king, “for all of his symbolic importance, doesn’t have that transactional element.”

“Trump doesn’t have much of incentive to be thin-skinned just now,” he added. “In terms of what that means generally for the relationship between the two countries, its a bit early to say.”

Trump offered Charles high praise on Wednesday while appearing to throw a jab at Starmer over the war with Iran.

“If that were up to him, he would have probably helped us with Iran,” Trump said while sitting in the Oval Office.

British monarchs are subject to rules and norms meant to prevent them from taking overtly political stands.

Gaskarth also praised Charles for putting distance between himself and the former Prince Andrew, who was arrested in February on suspicion of misconduct in a public office in relation to his friendship with Epstein.

Mountbatten-Windsor has always denied any wrongdoing in connection with Epstein. He was arrested but not charged with any offense.

Mountbatten-Windsor was stripped of his royal patronages, military affiliations and “HRH” title in 2022 by his mother. Charles has since taken more drastic steps, and in October he largely severed the family’s remaining ties with his younger brother.

Charles’ actions have “allowed him to continue to speak with authority,” added Gaskarth.

In one of the few concrete announcements connected to the trip, Trump said in a Truth Social post on Thursday that "in honor of" Charles' state visit, he would be removing some tariffs and restrictions on Scottish whisky.

He added: "The King and Queen got me to do something that nobody else was able to do, without hardly even asking!"

But those hoping that Trump’s fondness for Charles would erase the president’s irritation with Starmer were likely disappointed Thursday.

When asked by Britain's Sky News whether the state visit would help improve his relationship with Starmer, Trump responded: “I can’t give you an answer to that.”

“I like Keir Starmer very much, but I think he’s made a tragic mistake on immigration and a tragic mistake on energy,” Trump added, repeating sentiments expressed before the king came to town.