He won global acclaim for his deft interaction with President Trump last week, and his historic address to Congress, but King Charles is already looking for his next challenge, according to officials who travelled with him to the United States and Bermuda.
"This is a man who is absolutely driven by duty. Driven by service," says a senior palace aide involved in the trip.
"He’s not a man to dwell long on what some may consider yesterday’s successes, he is always looking towards tomorrow’s opportunities, so generally we’ve tried to encourage him to feel positive - and he has, about the way that the American leg has gone in particular, but his mind is already on what he can achieve next rather than what he achieved this week."
While the palace is typically hesitant to use the word "historic", officials concede that the term does apply to this visit, not least because it marked the 250th anniversary of US independence, and it was the first time a King had addressed Congress.
Charles won praise for including in his speech some of the issues that have divided the Trump administration and the UK government in recent months. However, he raised Ukraine and NATO during the "high-stakes" address because of his own personal concerns, as well as those of the government.
"It's a measure of how much he personally cares," says the aide.
© Chris Jackson/Getty ImagesA king 'guided by truth'
While the King’s confidence in gently asserting the British view on contentious issues may have surprised some, those who worked on the speech with him were not concerned.
"First, what the King says will always be guided by the truth," says one. "Two, it will be guided by conscience. And three, they’re all observable facts. Everything that is in that speech is an observable fact. And so, I think we felt very comfortable with the King speaking as he did."
It helped, of course, that the King and the President - along with the Queen and First Lady - got on famously during the four-day visit.
"They get on very well. And it’s not just the King and the President. It’s all four of them with each other," says the senior aide. "The Queen and the President. The Queen and the First Lady. The King and the First Lady. The King and the President.
"It’s a pairing, sort of unlikely though it might be in many ways… I mean, given some of the issues that have presented themselves in the bilateral relationship, you’d think it might all be a bit tricky. But far from it. And the warmth that you see in public is absolutely the warmth you see in private."
© Getty ImagesAlongside the more serious dialogue, behind the scenes in the Oval Office, "there was an awful lot of warmth and laughter," a far cry from some of the public comments President Trump has made about Sir Keir Starmer in recent months.
But officials are clear that the King and the government are not in competition.
"The King is there to support the government, to help the government. It was at the government’s request, of course, that he undertook this visit," says the aide. "And the King and the Queen have been able to help the government in any way and to get the relationship perhaps more widely understood by a wider number of people without some of the noise of current affairs."
Meanwhile, the visit has already produced tangible results. Within hours of the King and Queen’s departure from Washington, DC, the President lifted tariffs on Scottish whisky, an objective the government had been trying to achieve for many months.
For those involved in planning the trip, in the face of significant opposition from some quarters, it was a vindication of sorts.
"What looked like risk and challenge was also a phenomenal opportunity," says one. "One that was grasped in both hands by the King, and we shall leave you to conclude what the outcome of that was."
© Saul Loeb - Pool/Getty ImagesBusy in Bermuda
Following his triumphant visit to the United States, the King made a historic first visit to an overseas territory as monarch, spending a day and a half in Bermuda, where he received a rapturous welcome.
He might have been forgiven for spending the two-hour flight from Washington, DC, relaxing after a job extremely well done.
But within 10 minutes of take-off, having changed into a lightweight suit for the warmer climate, he was working his way through his briefing notes for Bermuda and official papers in his red box.
On his drive from the airport, the King was greeted by huge groups of people who had waited on the roadside in the rain to see him. Despite the weather, he wound the windows of his car down to wave back.
© Getty ImagesLarge, enthusiastic crowds meant engagements overran, but nobody minded the delays.
"The King has greatly enjoyed it. It has been very busy, and the crowds have been so huge they have made us extremely late, but no one minds about that when you feel that you’re doing some good here, showing that this island matters to Britain, because it certainly matters to the King."
Speaking ahead of the final day of the trip, which saw the King open a new Coast Guard station and attend the launch of a UK Space Agency observatory, a senior palace aide concludes: "So long as it all goes well… we’ll sit on the plane and think that was a week well spent."
