The King relishes the "tough parts" of his role and will continue to be used in "politically charged situations", a senior palace aide said at the end of the King's tour of the Caribbean.
Over the past nine days, the King visited the Bahamas, Guyana and Antigua and Barbuda and has been used as "a great secret weapon", the aide said.
Questions over whether the UK should apologise and pay reparations for its role in the transatlantic slave trade were a theme of the visit.
"I think what we're seeing is a very clear pattern emerging of the government asking the King to head into quite politically charged situations, quite challenging situations," the aide said.
"We have to tread quite a careful line sometimes between government policy and the King's role."
The leadership of all three countries visited on the Caribbean tour wanted reparatory justice.
"I would say, in the round, this has been a complex visit. It's been challenging. It's been exhausting," the aide said. "But the takeaway is that it's been very successful and I think the King has demonstrated his statecraft both by word and deed."
Most of the King's visits outside the UK have seen him draw on some delicate diplomatic skills on behalf of his government.
In the US, he used his speech to Congress to remind President Donald Trump of the UK's value as an ally.
A year earlier he made a flying visit to Canada to welcome new Prime Minister Mark Carney as the latter faced an onslaught of threats and insults from Trump.
Visits to Germany and France in the early part of the King's reign were designed to establish new UK alliances post-Brexit.
"The King is not just King for the easy parts of the job, but the tough parts of the job, too," said the aide.
"In fact, that's probably the part of the job that he relishes most, whether that's leading on the environment, whether it's renewing and refreshing and reinvigorating relationships with nations where there have been some complex political issues at play, that is what he lives and breathes for."
The senior palace aide has worked closely with the King for many years and has a unique insight into his work and what motivates the monarch.
"He is able to reach the parts that dare I say politicians probably couldn't quite have reached," he said wryly.
The intervention of Prime Minister Andy Burnham saying he was open to the UK apologising for its role in the slave trade midway through the Caribbean tour only intensified the conversations.
The senior palace aide dismissed any suggestion that Buckingham Palace was surprised, even blindsided, by the shift in the government position saying they were told about it in a "timely manner".
English authorities and the monarchy were prominent participants in the centuries-long slave trade which saw millions of Africans enslaved and forced to work, especially on plantations in the Caribbean and the Americas.
Asked directly if the King would apologise for slavery, the senior aide laid out the chain of command in a constitutional monarchy.
"The King is the crown, the crown is the state, the state is run by an elected government, so we have to see how this whole situation plays through."
Since the start of his reign in 2022, the King has had four prime ministers - it's been a quick turnover rate with the King having to establish a new relationship each time, helped by their weekly audiences. Those close to the King view his early encounters with Burnham as a positive start.
"They get on very well. I see them together every week," explained the royal aide. "It genuinely is a good relationship, but as it is with all the prime ministers and all the ex-prime ministers as well."
Royal tours may look pretty but they can be gruelling.
There were about 40 engagements on this tour - many of them carried out in temperatures of around 35C with stifling humidity.
While the King, who is still undergoing treatment for cancer, will be 78 years old next week and the Queen will celebrate her 80th birthday next July, they are both still managing the rigours of royal visits when many of their friends are enjoying retirement.
"This is literally what he was born to do, he's very good at it, and he enjoys the reaction he gets from people in the doing of it," the aide said.
He added the King and Queen's bond after 20 years of marriage helped get them through the trickier sides of their work when things have "gone a bit wonky".
Royal tours always throw up those "wonky" moments.
In Antigua and Barbuda, at a rally to mark the country's Independence Day, a sudden downpour left the King drenched, without an umbrella and looking momentarily cross.
"You know sometimes things don't work entirely according to plan, but it was very quickly resolved, and as we saw, he was laughing… he thought it was genuinely funny," the royal aide recalled.
And in the Bahamas, the King joined dancers during a Junakanoo, a traditional carnival celebrating the culture of the islands dating back to the days of slavery.
In his speech the King spoke of the slave trade as a shameful chapter that filled his heart with sorrow as he delivered his main speech at the Commonwealth Heads of Government meeting.
He was addressing a room full of leaders where many wanted him to say sorry, offer reparations or in some cases, be removed as their head of state.
The Antiguan Prime Minister, Gaston Browne, hosted the King and Queen but wants major change including moving his country towards becoming a republic.
He said he also wanted to see "structured, inclusive dialogue on the enduring consequences of slavery and colonialism".
Buckingham Palace knows the direction of travel. In 2021, Barbados removed the British sovereign as head of state. The mood was of a divorce where all parties still want to be friends… if possible. It's given neighbouring countries a taste of a something different.
"The King and the royal family are there to serve the people of these regions for as long as they wish," the senior royal aide said. "But if they don't wish it anymore, then we really are fully open to that. The family serves when it's wanted and if not, then a new arrangement can be found."
