Two things strike me as I walk with the Prince of Wales around the grounds of Dumfries House, his Georgian gem in the old coalfields of East Ayrshire.
The first is how clean it all is, right down to the spotless pig pens.
‘Very Mr McGregor,’ he says proudly in his walled garden. Except that Beatrix Potter’s rabbit-chasing villain never had a shed as smart as this.
The second is the complete absence of notices.
There are no instructions telling you to stay off the grass or keep to the path or not to smoke.
The Duke of Wales attending a reception in Ghana on the third day of his tour of West Africa
Helping hand: The Prince of Wales cuts into a birthday cake made for him and other guests
The house and grounds are open to the public all year round, whether the Prince is in residence or not.
Yet there is not even a sign, let alone a rope, to prevent people from sitting on one of the world’s finest collections of Chippendale furniture.
‘The Prince wants it to feel like a home, not a museum,’ explains chief guide Alex MacDonald.
If someone appears about to park themselves on a Chippendale chair or sofa — it seldom happens — they will just be quietly asked to refrain.
Here, in microcosm, is a glimpse of the sort of monarchy we can expect from a man who likes and expects things to be done properly but who, equally, understands that royalty is a two-way process.
The Prince of Wales and the Duchess of Cornwall attending a lavish reception in Ghana
His critics call him a fastidious old fusspot and a meddler.
His devotees speak of a man driven by a lifelong urge to promote excellence for all, whether in the arts, housing, food or any other aspect of the human condition.
As our future King prepares to celebrate his 70th birthday this month, I have spent time in the princely orbit to see for myself.
I have talked to those close to him, about how his life is so much more settled these days, thanks, in major part, to the Duchess of Cornwall (his second marriage will soon have outlasted his first); about the bedlam when the grandchildren descend (they call him ‘Grandpa Wales’, a touching echo of the Queen’s own relationship with George V whom she called ‘Grandpa England’); about the way he increasingly consults the Duke of Cambridge in all major family decisions; about his hopes that, while his sons have created new charity networks, one of his grandchildren — maybe George — will one day take on the stewardship of his own.
Royal observers may fixate on the likely complexion of the next reign and the extent to which he might rattle the monarchy or the Government (or both).
Yet the Prince’s sights, increasingly, are focused on what will follow him.
It is why he remains as passionate as ever about the future of the planet — and our capacity for ‘b*****ing’ it up.
At home, however, he has seldom been more contented in his roles as grandparent, father, husband and son.
Just last week, he stepped into the Duke of Edinburgh’s shoes as consort for the state visit of the King of Holland, the first time he has done so.
Viewers of next Thursday’s BBC1 documentary, Prince, Son And Heir: Charles At 70, will see the Prince and the Duchess of Cornwall as an endearing double act.
‘What I love about this is the clackety clack, clackety clack,’ says the Prince with childlike enthusiasm as they trundle along the Heart of Wales Railway Line.
The Duchess is less thrilled. ‘It sends me to sleep,’ she chips in.
His sons offer a fond, irreverent portrait of a hyperactive soon-to-be-septuagenarian.
‘He takes his policemen hedge-laying. Some of them come back covered in blood,’ says the Duke of Sussex.
‘They come back looking like they’ve had a fight,’ adds the Duke of Cambridge.
Taste test: Prince Charles tucks into a slice of cake at the luxurious reception in Ghana
Prince Charles with son Prince William and grandson Prince George at the Trooping the Colour ceremony in 2015
What is clear is that the Prince is keener than ever to leave his mark. Again, he is looking far beyond this reign or the next.
At Birkhall, his Highland home near Balmoral, he put in a plantation of trees to mark the birth of Prince George.
‘It will be quite amusing for him, I hope, as they grow up and he grows up.’
It is the same at Dumfries House, the estate set in 2,000 acres of Ayrshire which he saved for the nation in 2007 when its owner, the Marquess of Bute, put it on the market to pay death duties.
Just as the whole lot — including the unique Chippendale collection specially made for the house — was about to be flogged, the Prince stepped in with a £20 million mortgage.
That was just before his 60th birthday. I remember it well because I was interviewing him for a documentary at Birkhall.
Here we are, a decade later, as I join the Prince and a small group of benefactors and charity bosses for an overnight stay at Dumfries House.
So what has changed in the meantime? He has streamlined his charities into three groups and is increasingly sharing duties with the Queen.
The man himself, however, is still the same blend of humour, self-deprecation, evangelism and Eeyore-ish frustration as he reflects on life at 70.
‘I find that things can sort of stop working so I have to write it down or I forget it!’ he says, whipping out a notepad and pencil from one pocket in his gardening jacket.
He then plucks a pair of secateurs from the other. Does he feel optimistic about the world as he enters his eighth decade?
‘I would be if we would just stop b*****ing about with the planet. I just worry about the sort of world my grandchildren are going to live in,’ he says, rattling off chunks of a new French report on climate change.
Having made his first major public speech on the evils of plastic at the age of 21, does he now feel vindicated that the rest of the world has woken up to the threat?
‘I don’t know if it’s made any difference,’ he sighs, ‘but I had to say something.’
His response to the environmental challenge is to put stuff back. As with his hedge-laying, the tree-planting is frantic.
‘I won’t be around to see the results of those,’ he says cheerfully, pointing to an avenue of new limes he calls the Duchess of Rothesay’s Walk. (When in Scotland, the Prince and the Duchess use their Rothesay titles.)
Prince Charles tucking into some cake at the British High Commissioner’s residence in Ghana
Another new arboretum stretches out alongside Lugar Water, the river running through the estate.
‘It really was the most appalling mess before with a few conifers and a bog,’ he says proudly.
During the Bute years, the estate was sealed off from the outside world.
The last Dowager Marchioness spent her widowhood here, reputedly watching racing on a small telly while her Labradors lounged around on the Chippendale sofas.
The locals, however, were never allowed near the place.
Following the Prince’s purchase, everything changed. The house is open while people can park and tour the grounds for nothing.
The estate is also a campus, with six free educational centres already on site — for textiles, farming and so on — and two more on the way, all of them under the auspices of the Prince’s Foundation.
Each week, the Prince receives a detailed estate report, and he likes to check it all in person, so we are on a brisk tour of inspection rather than an afternoon stroll.
The Duchess of Cornwall is not here today but this little group includes a family member who plays an increasingly key role in this side of the Prince’s life, his first cousin, the Earl of Snowdon.
Previously Viscount Linley, he is now vice-president of the Prince’s Foundation.
As a former carpenter, Lord Snowdon wants to beef up Dumfries House as an education centre for arts and traditional crafts.
‘The Prince and I just want to help people make things,’ he explains.
A monthly farmer’s market is doing a busy trade on the drive as we walk past in the rain. Local baker Ameena Nur dashes out from behind her bread stall.
It turns out that she got her Jeju’s Bakehouse business off the ground thanks to a Prince’s Trust grant back in January and she wants to thank him in person.
She presses an oat and honey loaf into his arms.
A member of the Clarence House staff whispers: ‘I know you’re going to think that was staged but it really wasn’t.’
Since the trust has now helped nearly 900,000 people — even the Jimmy Choo shoe empire was built on a trust grant — these encounters are apparently happening with increasing regularity.
Regeneration needs cash, however. Dumfries House is now the largest employer in the area after the council but receives no grants for its educational work.
In the nearby town of New Cumnock, the Prince’s Foundation has reopened the local swimming pool and saved the old town hall from demolition.
Prince Charles and the Duchess of Cornwall are greeted by crowds of well-wishers in Ghana
Unemployment has been high since the closure of the mines. Yet nearly all who enrol on Dumfries House courses such as ‘Get Into Hospitality’ end up with a job.
Some of those trainees are serving at the Prince’s black-tie dinner in the main house later on.
Three tables are set for a dinner of hake and venison. The Prince has been attacked for courting billionaires but it is donors who keep all this ticking over.
On his right is an American heiress with two charitable foundations.
On his left is Patty Hearst, the granddaughter of the American publishing magnate, William Randolph Hearst.
Kidnapped while a student in California in 1974, she was indoctrinated by her captors into a life of armed robbery, captured, imprisoned, released by President Carter, pardoned by President Clinton and now runs her own charity. Tonight she is next to a future King discussing the jobless of Ayrshire.
There are no speeches. After dinner, the Prince leads his guests through to the Tapestry Room for coffee and a bagpipes recital. Everyone gets a chat.
Our little group discuss his ambitions to restore his beloved red squirrels to this part of Scotland.
‘I’m trying very hard but the problem is keeping the ghastly grey ones down,’ he says.
He bids goodnight at 11pm and we retire to the boutique hotel he has built at the end of the drive.
A few days later, I see him in very different circumstances. He is touring the headquarters of the London Ambulance Service.
He is shown inside a brand new £155,000 ambulance and an old 1949 Daimler model from the service’s collection.
Informed that they also have a horse-drawn model from 1891, he replies: ‘That must have been lovely!’
‘It gives everybody a lift,’ says 999 despatcher, Karen Clark, 46.
The Prince’s sons have both paid recent visits, she says, pointing to the crown, part of the LAS emblem on her uniform.
It is a reminder of royalty’s role in conferring a type of national recognition which cannot be provided by politicians or celebrities.
Later on, the Prince is back in black tie at Buckingham Palace, with the Duchess, for a 70th birthday tribute from the arts.
Produced by the Royal Opera House and the Royal Shakespeare Company, Sir Kenneth Branagh and Dame Judi Dench reprise parts from Henry V and A Midsummer Night’s Dream.
There is some sublime Wagner. Stephen Fry reels off the birthday boy’s attributes and reminds us ‘how freakishly lucky we are’ to have him.
Among the guests is a man who is well-placed to assess all this.
Sir Eric Anderson taught Prince Charles at Gordonstoun, Tony Blair at Fettes and both David Cameron and Boris Johnson at Eton.
He was headmaster of Eton when Prince William was accepted, and returned as Provost during the Harry years. (Interestingly, he says his most distinguished pupil is none of the above but a Fettes boy called Angus Deaton — who went on to win the Nobel Prize for Economics).
Sir Eric and his wife, Poppy, have been friendly with the Prince ever since his schooldays.
‘First of all, the Prince has been an extremely good father. Not everyone can bring up two sons on their own so well and I’ve seen a lot of sons.’
He regards what the Prince has done at Dumfries House as emblematic of the man.
‘If he was the fuddy-duddy he’s painted as, he’d simply have renovated the house, but he used it to revive a whole community.’
The Prince, he adds, has guts, whether speaking out on unfashionable issues or taking his first parachute jump.
‘His pilot came up and said, “Sir, we’ll go over the drop zone so you can see it and circle and then come back and you can jump,” and he said: “If you don’t mind, I’ll go first time thank you.” ’
Sir Eric, whose Gordonstoun duties included overseeing the school play, recalls the Prince’s natural aptitude for theatre and his first starring role.
‘No one doubted he should be Macbeth and he was very good,’ he says, joking that when the Prince’s father had been in the same play at the same school, he’d had the walk-on part of Donalbain.
What sticks in his mind, though, is the Prince’s sense of humour.
‘When the costumes were delivered, the Prince tried on Macbeth’s crown and said: “We’ve got better crowns than this at home.” Everyone fell about laughing. The public don’t always see the sense of humour but I think you must need that to survive.’
It will, no doubt, be invaluable when the time comes to put on a ‘better’ crown at home.
For now, the Prince seems perfectly happy where he is.