Britain's Royal Gambit: King Charles in Congress Is Both Smart and Damning

As King Charles arrives in Washington to address a joint meeting of Congress on Tuesday, the British government finds itself in a position that is simultaneously clever and desperate. I want to explain why I think both of those things are true at the same time, and why the tension between them is the real story.

Let me start with the timeline, because the timeline matters more than anything else here. The visit was not cooked up in response to a crisis. Keir Starmer personally hand-delivered King Charles's invitation to Trump² in the Oval Office on February 27, 2025, just five weeks into Trump's second term. Trump made a reciprocal state visit to Windsor Castle in September 2025, where he was treated to brass bands, scarlet-clad guardsmen, and a banquet dripping with gold leaf. The return visit to America was planned around the 250th anniversary of the Declaration of Independence. This was, in other words, diplomacy running on schedule. The Crown was deployed as one instrument in a toolkit that, at that point, appeared to be working. Britain was the first country to secure a trade deal³ with the Trump administration, announced in May 2025.

Then the Iran war started on February 28, 2026, and everything changed.

The collapse happened fast. Starmer refused to let US aircraft use British bases for offensive strikes on Iran, citing international law. Trump responded with escalating fury. He called Starmer "a loser" at private dinners⁴, said he was "not Winston Churchill" and compared him to Neville Chamberlain. He dismissed the Royal Navy's aircraft carriers as "toys." Asked about the special relationship this month, Trump replied: "Not good, not good at all."¹ A leaked Pentagon email suggested the US could reassess support for Britain's sovereignty over the Falkland Islands. And Trump threatened to impose a "big tariff"⁵ on the UK over its digital services tax, warning that the trade deal he signed could "always be changed."

So the visit that was conceived in diplomatic sunshine is now landing in a storm. And this is where the analysis gets interesting, because you have to hold two ideas in your head at once.

Idea one: using the Crown is genuinely smart. Trump's fascination with the British monarchy is not a secret. In "The Art of the Deal," he wrote that he got his "sense of showmanship" from watching the Queen's coronation on TV as a boy. He described his September trip to Windsor as "amazing"¹ repeatedly. When asked whether the royal visit could help repair relations, Trump told the BBC last week: "Absolutely, the answer is yes." He's even insisted that the political chill with Starmer won't affect the visit: Charles "has nothing to do with that," Trump said in March¹², referring to NATO. Britain identified a genuine asymmetry in Trump's psychology and is exploiting it. That is not weakness. That is targeting.

The Congressional address itself is structurally designed to produce a specific effect. When a head of state addresses a joint meeting of Congress, every member who stands and applauds is on camera doing so. That creates a public association between those legislators and the bilateral relationship. As former British Ambassador Peter Westmacott told CNN¹, the King "provides an opportunity for private conversations on some really important issues," even if he won't have "the kind of conversation with the president" that the Prime Minister would. The mechanism here is environmental: raise the domestic political cost of treating Britain dismissively by making the relationship visible and bipartisan in Congress. House Speaker Mike Johnson has already signaled warm reception, telling Charles he would be "well received."⁸

Idea two: the circumstances are damning regardless. Here is what I keep coming back to. Starmer's government was hoping the visit would "shore up the future"⁷ of the special relationship, which multiple outlets describe as being at its lowest point since the Suez Crisis in 1956. British Foreign Secretary Yvette Cooper acknowledged the visit is "really symbolic of the strength of our relationships" while simultaneously conceding the countries "take different views" on Iran. Starmer himself defended the trip by saying "the monarchy, through the bonds that it builds, is often able to reach through the decades"¹² to bolster relationships.

Read that sentence again carefully. Starmer is saying, in public, that the monarchy can do something that he, the elected Prime Minister, currently cannot. CNN's own reporting put it bluntly: "Charles has become something of a trump card for the British government."¹ The move shows "how Starmer's government planned to handle Trump in his second term: play to his penchant for flattery and royalty — and hope to reap rewards." That framing is both admiring and revealing. When your diplomatic strategy toward your most important ally is built around one man's vanity and another man's crown, you are not operating from strength.

I want to be precise about my position. The decision to proceed with the visit was correct. Canceling it, as Liberal Democrat leader Ed Davey demanded², would have been pointless self-harm. And deploying the Crown against a president who is genuinely susceptible to its appeal is rational instrument selection. But calling it sophisticated strategy obscures the underlying diagnosis. The UK-US trade deal, reached when relations were warm, is now under explicit threat. The 10% baseline tariff on British goods remains in place⁹. Trump is threatening new tariffs over the digital services tax. Only 30% of Britons¹⁰ now believe the special relationship even exists, a 17-point drop in one year. These are not problems a 20-minute speech to Congress can solve.

The constitutional constraint matters here too. King Charles cannot negotiate⁶. He "cannot negotiate NATO commitments, tariffs or Iran policy," as one analyst told Al Jazeera. He can, at best, "create a public setting in which both sides can step back from open hostility without appearing weak." That is a real and useful function. But it is a de-escalation function, not a deal-making one. The actual substance — tariff negotiations, defense commitments, the digital services tax dispute — still requires Starmer to pick up the phone with a president who privately calls him a loser.

There is also a risk that gets insufficient attention. Trump's approval rating sits at roughly 35-36%¹¹ across recent polls, with two-thirds of Americans disapproving of his handling of the Iran war. King Charles is stepping onto a stage defined by that polarization. House Democratic leader Hakeem Jeffries has already framed the visit by blaming Republican policies⁸ for straining the relationship. The Crown's utility depends on it sitting above partisan coding. Every time the visit is interpreted through the lens of the Trump-Starmer feud, that neutrality erodes a little.

My overall assessment is this: Britain is playing its strongest available card. That the strongest available card is a 77-year-old monarch undergoing cancer treatment, addressing a Congress he cannot negotiate with, on behalf of a prime minister whom the president openly despises, tells you everything you need to know about the hand.

What to watch next: the real test is not whether Tuesday's speech gets a standing ovation. It will. The test is whether, in the weeks following the visit, Trump's rhetoric toward Britain softens, the trade deal survives intact, and the digital services tax dispute gets resolved without punitive tariffs. If none of those things happen, we will know that the Crown's soft power, however impressive in the chamber, did not translate into the hard outcomes Britain actually needs. I suspect we will know by midsummer.