The King is "managing" his cancer and living life as "normal as possible," a senior royal aide has said as Charles and Camilla completed their whirlwind tour to Canada.
The monarch's treatment is ongoing but neither the Queen nor his most trusted advisors can convince him to slow down.
Their Majesties carried a series of back-to-back engagements during a two-day visit to Ottawa, which culminated in the King delivering a 26-minute speech from the throne, in English and French, during the state opening of Parliament.
"The thing you learn about this illness [cancer] is that you just manage it. And that's what he does. Medical science has made incredible advances and I genuinely see no difference in him," a senior royal aide said. "As long as you just do what the doctors say, just live your life as normal as possible and that's exactly what he is doing.
"It's no secret that he is still having treatment but because he is incredibly fit, he is just dealing with it all incredibly well. As everybody knows he is driven by duty, so he just gets on with it."
© Victoria Jones/ShutterstockWhile the King and Queen will take a break from their public duties for the rest of the week, aides are "planning the programme as usual, trying to lighten it a little bit" but without "much success".
The busy royal summer calendar encompasses high-profile events including Trooping the Colour to mark the King's official birthday, Garter Day at Windsor Castle, Royal Ascot and an incoming state visit from France's President Macron in July.
Charles and Camilla were greeted warmly in Canada, with the couple taking the time to shake as many hands as possible during a community event at Lansdowne Park and during a walkabout as they walked to the war memorial after the state opening.
© Getty ImagesThe King was "very touched" by the reception from Canadians, with a senior royal aide adding: "To go to a realm of which you are King, but in which you don’t actually live, is a big thing when you do it for the first time, as we saw in both Australia and now Canada.
"It is a reset of that relationship, and for Their Majesties to see so many people turn out and to be so thrilled to see them was fantastic. As The King put it in his departure message that came straight from the heart: 'It was the warmest of welcomes and the fondest of returns to a nation and a people we love'."
© Victoria Jones/ShutterstockWhile there's always going to be a strong sense of continuity within the monarchy, Charles III is also putting his own stamp on defining the Carolean era.
A senior royal aide said: "Almost three years on, everyone has a clear impression of what that is and the role that he will play - one that is both traditional for the monarchy and distinct to His Majesty.
"Leveraging on the long relationships he has built over the years, he has enhanced his role as a global statesman on so many issues, wielding soft power to the benefit of all the realms and commonwealth nations at a time of great international challenge.
© Hannah McKay/Pool/Shutterstock"Underpinning it all are the four big Cs at the heart of his personal value system - communities, climate, commonwealth, culture - with the smaller c of his own illness being used to show support for others affected by cancer.
"He has dealt with his illness in a very human way and the way he's engaging with the public at a very human level. I think we now have a clear idea of what the Carolean age looks like and what it stands for - now and hopefully for many years to come."
