Tuesday marked a particularly poignant day for King Charles.
While the monarch celebrated his 19th wedding anniversary with his wife Queen Camilla in private, it was also tinged with sadness, given it marked three years since his father Prince Philip passed away.
The late Duke of Edinburgh was just two months shy of reaching his 100th birthday when he died in April 2021 during the UK's national lockdown.
But Tuesday was also the 22nd anniversary of the funeral of Charles' grandmother, the Queen Mother, who he was exceptionally close to, especially given his, at times, fractured relationship with his own parents.
The King, 75, has been open about how close he was to the Queen Mother and how he models his own grandparenting style on hers.
On becoming a grandfather, Charles has previously said: "It's a different part of your life. The great thing is to encourage them. Show them things to take their interest. My grandmother did that, she was wonderful. It is very important to create a bond when they are very young."
While Charles and Camilla celebrated their wedding anniversary in private, the King did carry out a small-scale engagement at Buckingham Palace on the afternoon of April 9 – and received a rather unusual anniversary gift!
He welcomed Bank of England governor Andrew Bailey and chief cashier Sarah John to the palace's 1844 Room, where Mr Bailey presented the King with the first banknotes bearing Charles's portrait.
It was a milestone moment for the monarch, who is undergoing treatment for an undisclosed form of cancer, to see his image on the new polymer notes, just over a year and a half since the start of his reign.
He is only the second British monarch to grace the Bank of England's notes – and it is the first time one sovereign's image has been replaced with another.
Charles's mother, Queen Elizabeth II, was the first British sovereign to be given the honour in 1960 on a £1 paper note. Before this, Britannia was the only character to have appeared.
"We have come to present you with your bank notes," Mr Bailey told the King as he showed him a leather-bound booklet containing the historic banknotes.
"This is quite a big moment because we've never changed the sovereign on the bank notes because the Queen was the first sovereign to be on the bank notes."
Charles' new banknotes will be issued from 5 June, although the notes featuring his late mother's face will still be in circulation. New Charles notes will only be printed to replace worn-out ones and to meet any overall increase in demand, to minimise the environmental and financial impact, in keeping with the royal household's request.
During the meeting, the King also apologised for postponing their initial meeting, due to his health issues earlier this year. "Good morning Governor. I'm sorry it's a bit delayed this. I hope it isn't too delayed," Charles, who has been scaling back his public appearances and engagements, said.
But Mr Bailey replied: "Not at all. We're still in advance of launching them."
"Oh you are? Great," Charles remarked.