Video report by ITV Wales National Correspondent Rob Osborne
On the little finger of his left hand, the King wears a ring.
A closer inspection shows it is a gold signet, engraved with the symbol of the Prince of Wales.
It is suggested that King Charles III has rarely removed the ring from his finger since it was put there in the 1970s.
It is a reminder, should we need one, that although he was born to be King, he spent 64 years of his life as Prince of Wales.
King Charles III comes to the throne knowing more about Wales, Welsh history and Welsh culture than any other monarch probably since King Henry VII from Pembrokeshire.
Lord Dafydd Elis-Thomas has known the King since they were students.
As a former leader of Plaid Cymru, a member of the House of Lords, a former Presiding Officer of the Welsh Assembly, and a former minister in the Welsh Government, their paths continued to cross.
"I told him a few years ago that he was the Prince of Wales that had the most experience and knowledge of Wales as a country. He's got the best possible CV of any royal that's been on the throne of the United Kingdom."
But the relationship between Wales and the former Prince of Wales had at times been more complex.
It began at the closing ceremony of the Empire and Commonwealth Games held in Cardiff in 1958. The Queen announced that her eldest son would be made Prince of Wales that day.
She said: "I intend to create my son Charles Prince of Wales today. When he is grown up I will present him to you at Caernarfon."
The boy Prince was listening to the news on the radio at school.
"I remember being acutely embarrassed when it was announced", he later recalled. "For a little boy of nine, it was rather bewildering."
But Wales changed as the deferential 1950s made way for the swinging 1960s.
Social movements grew. Protesters took direct action demanding protection for the Welsh language, Cymraeg. Welsh Nationalism was on the rise.
A proposal was made to flood the Tryweryn valley in Gwynedd to create a new water supply for Liverpool.
The Welsh-speaking village of Capel Celyn was earmarked for demolition.
Thirty five of the 36 Welsh MPs opposed it. Public opinion opposed it. But it went ahead. In 1965 the villagers were evicted - their homes, chapel, school, and history levelled to the ground.
Even now, the slogan "Cofiwch Dryweryn" or "Remember Tryweryn" is seen across Wales. Adopted as a rallying call by a new generation who want an independent Wales.
For Prince Charles, the timing could not have been worse.
For some, the investiture, planned for the summer of 1969, became a focal point of anger.
The idea of a new Prince of Wales repelled them, believing the last true native Prince of Wales died many centuries ago.
Owain Williams was one of them.
In 2018 I made a documentary recalling the events. He explained his feelings.
"I am Welsh. I feel I am a patriotic person, and the idea of having a foreigner installed in Caernarfon Castle in Gwynedd, as a so-called Prince of Wales, I find insulting to me personally and my nation."
Protest songs were written.
The Welsh folk singer Dafydd Iwan sang “Carlo” mocking the Prince. It became the movement’s anthem.
Despite the objections, even bomb plots (two men were killed after the device they were carrying exploded at the council offices in Abergele), the ceremony went ahead as planned on 1st July 1969.
Man would land on the moon 15 days later. At times, that must have seemed the easier of the two missions.
The streets of Caernarfon were packed. Nineteen million watched at home, and five hundred million watched around the world.
Speeches were made in Welsh, the first at the Urdd Eisteddfod of 1969.
Before the young Prince began, a group of protesters stood up, signalling their objections and walked out.
Once it started the Prince promised, in Welsh, not to let the language die without a fight.
In the decades that followed, the relationship relaxed, people moved on.
The former Prince of Wales fronted documentaries for ITV Cymru Wales, then known as HTV.
One from 1969, which focused on rural Welsh, life stands out.
In it, he encountered an old Welsh cob breeder and farmer named Dafydd Edwardes.
His was a simple way of life, preferring the old methods of living off his land.
Asked by the Prince if he wanted to make any money, Dafydd said no.
"As long as I've got enough to get food and the pleasures I want, I'll be quite happy," said Mr Edwardes to an amused Prince.
In a speech marking 50 years since the investiture, Prince Charles called him "one of the most intriguing characters I have ever come across."
He continued: “The time I spent exploring and meeting such remarkable characters, helped me begin, just begin, to understand something about the profound connection that exists between the landscape, the rural and agricultural communities and the culture and language of Welsh people.”
The Prince and Dadydd Edwardes came from different worlds. Dafydd was passionate about sustainability, pro-tree planting, anti factory farming. “The old ways” he said, were better. Perhaps the old man made a lasting impression on the young Prince.
Prince Charles meets Welsh cob breeder Dafydd Edwardes
The Prince's bilingual contributions continued. He's been present at big occasions like the opening of the Welsh Parliament - The Senedd. He also had his annual 'Wales Week' - touring the nation each summer.
But in 2018, the second Severn crossing was renamed The Prince of Wales Bridge and old wounds reopened.
Did the people want it? Polling and petitions suggested not.
Some privately suggested the Prince wasn't too keen either.
As he unveiled the new name, he was at pains to stress how he wanted the name to reflect all of Wales' princes.
"My particular hope is that the Crossing's new name will bring to mind all those who, over these long centuries, have borne that ancient title "Tywysogion Cymru" and the different traditions and heritages that they represent," he said.
His Majesty also looked back at his six-decade personal connection with the nation.
"What an immense privilege it is to be associated with this remarkable land, whose name I have been so proud to bear for the past 60 years," he said.
"I have come to love and admire the character of her people: their passion, tenacity; their sense of fair play - "chwarae teg" - and, of course, their humour. Wherever I go, I am acutely aware that to bear this name is the greatest possible honour."
King Charles III has a Welsh home, Llwynywermod, a farmhouse in Carmarthenshire.
It is modest compared to most royal residences. Purchased in 2006 and quietly restored using the traditional method he champions.
This is where he came to reflect after the death of his father, Prince Philip.
He is part of the local community. Buying newspapers from the newsagent, his meat from the butcher.
As an ITV Wales Correspondent, I have covered many visits.
In 2020, Pontypridd was badly hit by floods. Within days the former Prince visited. The streets were packed, thousands coming to see him.
He spoke to shopkeepers struggling with their insurance companies paying out. He wanted to help.
His last visit as Prince came in July.
He and the Duchess of Cornwall spent time in the Rhondda. Walking the streets, meeting the crowds, listening to the local male voice choir.
The scenes have been repeated in communities across Wales for decades.
When he next walks the streets of Wales, he will do so as King.
In his first act as King, His Majesty made Prince William the Prince of Wales. The speed of that announcement surprised everyone, including Welsh ministers.
Perhaps he was keen to move quickly. Learning from his own experiences, limiting the room for opposition.
But the debate has already begun on whether there should be a ceremony to coincide with the title.
The King's old acquaintance Dafydd Elis Thomas has previously given his position.
"One of the issues I did raise with him was that I hoped there would never again be an investiture in Caernarfon castle," he told me this week.
The then-Prince is said to have laughed, looked at him, and replied: "Do you think I want to put William through what I had to go through?"
A strong hint not to expect a repeat of the scenes from the past.
The Wales of 2022 is different from the one of 1969. We have national institutions like The Senedd. Cymraeg is a growing language, not a dying one.
And what of the signet ring? Will the King continue to wear it?
But it's a public and a personal reminder of the bond he has with the nation whose name he bore for so long.