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As monarch, King Charles III is bound by constitutional convention to remain politically neutral. But that hasn’t stopped the UK government from deploying the king to advance its foreign policy agenda.
During their inaugural meeting, Keir Starmer presented Donald Trump with a letter from the king, inviting the president for a “truly historic” and “unprecedented” second state visit to the UK and a visit to the monarch’s private Balmoral residence.
Later that week, the government arranged for the king to meet Volodymyr Zelensky at the royal countryside retreat of Sandringham, to show support for the Ukrainian leader following his disastrous meeting with Trump.
The government is walking a tightrope: it wants to avoid tariffs from Trump, while continuing to support Zelensky and Ukraine. And it is using the king to help it do so.
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It is not unusual for governments to use monarchs to boost international relations, particularly through state visits. The monarch has a huge amount of soft power and the pomp and ceremony of a state visit can help governments achieve their foreign affairs aims.
State visits differ from regular diplomatic visits: they are the most formal way in which a foreign head of state can come to the UK, and happen just once or twice a year.
Visitors are greeted by the king and other members of the royal family with a ceremonial welcome accompanied by gun salutes on the Horse Guards Parade ground in London. They then travel back to Buckingham Palace in a carriage procession, where they enjoy a formal state banquet at which the monarch toasts the visiting head of state.
State visits are not cheap: Trump’s first visit cost £3.5 million in policing alone. But they can play a key role in diplomacy.
A state visit to France by Queen Elizabeth II in 1972 helped seal the deal on the UK’s third attempt at joining the the European Economic Community. And in 2024, the UK’s defence partnership with Qatar was “strengthened” following the state visit of the Qatari emir.
There is a danger that the monarch’s reputation is affected by hosting controversial heads of state. No doubt the palace PR team is less than enthused about the prospect of Charles being seen wining and dining Trump. The optics of hosting Trump during his first state visit reportedly put the late Queen Elizabeth in a “very difficult position”.
But monarchs have little (if any) influence over who they host for a state visit. Charles will have been advised by the government to invite Trump in accordance with the cardinal convention. This fundamental constitutional principle requires the monarch to act on the advice of the government.
Constitutional conventions are not legally binding. But in the UK’s constitutional monarchy, the monarch reigns but does not rule and power is exercised by democratically-elected ministers rather than the sovereign. Failure by the monarch to follow convention could spark a constitutional crisis, as fictional plays and dramas have long imagined.
This is why the late queen had to host some controversial and less-than-democratic figures. It even once led her to hide in a bush to avoid encountering Romanian dictator Nicolae Ceaușescu in the Buckingham Palace gardens.
And it is why Charles, on the government’s advice, will host Trump.
Laying on the royal charm
Usually, the public doesn’t see invitations for state visits, but we did see this particular letter. Signed “Yours most sincerely, Charles”, it feels particularly personal and designed to charm Trump, whose love of the British royal family is well known. The offer of an additional visit to Balmoral is a nod to the president’s mother, who was born in Scotland.
The king’s invitation seems to have done the diplomatic trick. Trump ended his meeting with Starmer by stating: “I think we could very well end up with a real trade deal where the tariffs wouldn’t be necessary”.
But the visit won’t be without controversy. In the days since, a petition asking for Trump’s invitation to be withdrawn has reached nearly 200,000 signatures. But Starmer has publicly dismissed calls to withdraw the invitation.
No doubt Charles himself is less than thrilled to invite the president, both after his recent behaviour towards Zelensky and his decision to pull the US from the Paris agreement, given the king’s advocacy on environmental issues.
Could the king raise such issues with Trump? Charles is bound by the doctrine of political neutrality: he must refrain from acting on political opinions. But that doesn’t mean there won’t be room for other senior royals not bound by the convention, like William, from doing so.
Indeed, as prince of wales, Charles himself showed opposition to controversial leaders, effectively boycotting Chinese state visits in 1999 and 2015 allegedly in support for the exiled Tibetan leader, the Dalai Lama.
The monarch plays an important diplomatic role, especially during state visits. While the leaders they host may be controversial, the monarch must respect constitutional boundaries. Nevertheless, with an outspoken king and heir, this visit could prove to be even more unprecedented than it already is.
Francesca Jackson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
