When the Prince of Wales popped in to visit young dairy farmers Kevin and Justyna Hughes, the circumstances were not exactly auspicious: they were living in an old caravan on their newly leased farm just outside Hereford.
The weather was so cold, the water had frozen, precluding them from even offering him a cup of tea. Moreover, as soon as the Prince arrived, so did the snow.
"We were a little bit nervous," says Kevin, 36, in his warm Welsh accent, "but he's not what you expect. He didn't mind at all. He came over to the yard to see the cows and have a look at our new milking parlour. He was so knowledgeable."
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"And when we met him at his 70th birthday party last year, he remembered everything about it," points out Justyna, 31. "His memory is out of this world," her husband marvels.
Of course, Prince Charles did not exactly stumble across the Hughes's caravan; the couple, with their daughters Chloe, five and Lydia, two, are tenants of Hill Barn, a Duchy of Cornwall farm – of which there are about 120, spanning 23 counties across the country, from the Scilly Isles to Scotland, from Devon to Kent.
The Duchy doesn't just hold farmland (nor make fancy biscuits – the Duchy Originals brand, now worth multi-millions, was licensed off to Waitrose a decade ago).
An enormous estate dating back to 1337, when it was established by Edward III for his son and heir, the Black Prince, its interests now include retail parks and new towns such as Poundbury in Dorset and Nansledan in Cornwall, which cover some 200 sq miles of the UK and generate $42 million in profit a year.
Now for the first time, this kingdom-within-a-kingdom has gone under the microscope in a landmark two-part observational documentary, Prince Charles: Inside the Duchy of Cornwall, that begins tonight, narrated by Amanda Redman.
Two years in the making, the film reveals a side to Prince Charles that few of the public see.
Headlines, this week, have focused on his admission he was moved to tears by the Duke of Cambridge declaring his burgeoning passion for farming, as he prepares to follow in his footsteps.
Yet for the largest part this is the future king at his most relaxed, working alongside his estate managers, farmers and tenants who live on Duchy land, where he pioneered organic, sustainable practices that once attracted mockery, but in the current climate perhaps mark him out as ahead of his time.
The camera catches him hedge laying – "I love spending a couple of hours doing this," he says with un-regal glee – and expertly apprising livestock. But it focuses most on the strength of his relationships with those who work and farm for him, some of which stretch back 50 years to when he first took over the Duchy, aged just 21.
No wonder then, that a key part of the team is his old friend the Countess of Arran, who is here today, nibbling fruit cake and drinking coffee in Kevin and Justyna's spacious farmhouse kitchen – a far cry from their old caravan, which she also remembers, having interviewed the couple for the farm tenancy two years ago.
Lady Arran sits on the Prince's Council, a small group advising the Prince of Wales over the Duchy of Cornwall, and has a remit to visit families like the Hughes in a wide-ranging pastoral role, keeping an eye, in particular, on the partners of Duchy farmers, who can sometimes feel isolated.
"I'm not here to be intrusive or to tell people what to do," she explains. "My job is to listen and to be able to go back to the Prince and say, 'This little gang are getting on so well.'"
Her rather smart accent belies her willingness to muck in. "Oh, lend me some wellies," she says as we head out to see the couple's 200 Jersey cows, who have some 230 acres to graze on. "I'll have to wash them," worries Kevin. "Don't be ridiculous," she retorts, "I'm perfectly happy with a bit of mud."
Outside, the yard and fields are immaculate, if not quite as grand as the grounds of Lady Arran's own historic home.
Born Eleanor van Cutsem (but known as Nell), she inherited Castle Hill in Devon from her mother, Lady Margaret Fortescue and has spent the past decades running the large estate with her husband, Arthur Gore, Earl of Arran, letting out 50 farms to locals and running 11,000 acres of woodland.
"I remember my grandmother taking me to visit the tenants on the farms; I used to go round on my pony," she says. "In the old days, you just rode into the farmyards but now of course, you call or drop an email first." Today's vehicle of choice may have four wheels rather than four legs, but she believes that there is still a place for the great estates. "They are a major part of the community; they create a sense of continuity."
As the 14th generation of the Fortescue family to live at Castle Hill – like the Duchy, her estate has third and fourth generation tenants in the same farms – she and her husband have already prepared for their succession.
They moved out of the "Big House" to a rather grand bungalow in the grounds, three years ago, making way for their eldest daughter Lady Laura, her husband James Duckworth-Chad (a former equerry to the Queen, Princes William and Harry attended their wedding) and their four young children to take over.
Similarly, in tonight's documentary, Prince William is seen meeting the tenants who will one day be his responsibility: "Don't worry," he says, "I intend to run things as my father did on the whole. I'm interested in the same things. Well, except the architecture…".
In time, of course, six year-old Prince George will inherit the Duchy; according to his father, he is already "obsessed" with the tractors.
This emphasis on keeping family and continuity at the heart of the Duchy means that tenants have to be chosen with care – especially given how rarely any of the farms come vacant.
Kevin and Justyna applied to run Hill Barn in 2017 as experienced dairy farmers, having worked in Kevin's native Carmarthenshire, New Zealand and most recently Abergavenny. They didn't expect to be picked, "but we had a good business plan and we could see that old farm could be renovated and made bigger," he says.
Once they had been selected and offered a 20-year tenancy, the Duchy paid for the house to be extended and improved, letting the Hughes consult on internal decoration and kitchen fittings. Anything portable – like new milking equipment – they had to buy themselves.
The couple moved on to the farm in that caravan in January 2018 with the Prince's first visit the following month. "We got a lovely letter from him, too," says Justyna. Tenants are also sent Christmas gifts personally chosen by the Prince – last year, two beautifully decorated china mugs – and were all invited to 70th birthday celebrations and, more recently, a garden party at Buckingham Palace.
The Duchy – having put faith in their tenants – clearly wants to keep them, too.
"It's wonderful for the farm and for the community," says Lady Arran. "The Prince loves seeing the land looked after well. The Duchy is his vision: a hugely successful business run with a heart."