Ever since his return to the Oval Office, the question of how to deal with Donald Trump has, for democracies and dictatorships alike, been at the top of the agenda of virtually every foreign ministry in the world.

The issue for democracies is a particularly thorny one. It once could be taken for granted that America – whether under Republican or Democrat administrations – was the leader of “the free world”. There might occasionally be differences between the US and its allies, sometimes serious ones: think of President Eisenhower’s savage treatment of Britain during the Suez Crisis or the estrangement between America and France over the Iraq War. Those difficult passages notwithstanding, democracies all knew which side America was on in the great global competition with the authoritarian world.

That is no longer so. In an environment in which America is no longer a reliable security partner, or – as I argued in this column recently – sees itself as leader of a more or less unified bloc of democratic nations, each democracy has to define its relationship with the US anew.

This is why the news last week that Trump had accepted King Charles’ invitation to visit the United Kingdom in September is important. It will be Trump’s first visit to another democracy since his inauguration. (His first overseas visit, to Saudi Arabia, is expected in May.)

The visit is not to be written off as mere ceremonial flummery – as, no doubt, many of Australia’s tunnel-visioned republicans will see it. In global politics, personal relationships matter. For Britain to secure Trump’s visit before any other democracy – paradoxically, at the invitation of its monarch – is a significant diplomatic coup.

It was the American scholar Joseph Nye who, in 1990, coined the term “soft power”: those emblems of national identity and cultural influence which can be every bit as important as more coercive forms of state power. Nye expanded on the concept in his hugely influential 2004 book Soft Power: The Means to Success in World Politics.

There is no more impressive manifestation of Britain’s soft power than its monarchy. Nobody – not America, not France, not anyone – can match the pomp and pageantry of Britain’s great state occasions. For a personality so hungry for respectability as Donald Trump, there could scarcely be a more prized invitation. And although King Charles may privately loathe Trump’s politics – and, perhaps, even the man himself – a lifetime schooled in the ethic of service means that he will use every advantage the majesty of his office affords to advance Britain’s interest in maintaining the best possible relationship with America.

The coup of securing Trump’s first visit is indicative of a broader reality: that of all the democracies, it is the United Kingdom which has the best chance to influence the Trump White House. The loathing of Europe among those around Trump – manifested recently in the WhatsApp messages of his Defence Secretary Pete Hegseth, accidentally shared with a journalist; and Vice President JD Vance’s insulting speech to the Munich Security Conference – has been largely directed at continental European nations, not Britain.

The fact that the United Kingdom is no longer a member of the European Union is, in their eyes, commendable: there is no important figure around Trump who didn’t applaud Brexit.