Only the coldest of hearts could fail to warm to Sarah, Duchess of York. Dotty and generous, she is bursting with energy and child-like joie de vivre.
"Oh, I am in every way a child," she agrees, in that "posh but not plummy" voice we remember so well from when she first burst into the Royal Family like a flamed-haired wrecking ball in the 1980s.
"It's who I am. It gets me into endless trouble. People think you're impossible or difficult if they can't relate to you, if you don't take life seriously. But the key to me is that I look at life with a child's sense of excitement and joy."
Doesn't she just. Who didn't fall in love with her all over again (while holding a nervous hand over our eyes) watching her at her younger daughter Princess Eugenie's wedding to Jack Brooksbank last month. There she was, breaking with protocol yet again to hug well-wishers in the crowd before entering St George's Chapel, Windsor Castle, reports Daily Mail.
And flumping down in her pew — mouthing to Princess Beatrice that she couldn't hold her tummy in any longer — before waving and beaming at friends in the congregation.
That beam told us that Fergie is back, her sense of mischief and fun undimmed: enveloped again in the public embrace, reconciled with the Royal Family after years in the wilderness.
Last week, I spent two days with her and this unprecedented interview and rare access — the most extensive in decades — gave me a singular insight into her character.
She speaks about her divorce from the Prince, which continues to baffle and fascinate 22 years after they stopped being man and wife — "We're the happiest divorced couple in the world. We're divorced to each other, not from each other."
She describes, with magnanimity, those wilderness years which left her in the surreal situation of having to watch her own daughters on TV every Christmas, as they joined the Royals at Sandringham, while she remained banned.
"I will watch Ben-Hur and really enjoy it, then watch the news and see how the girls are doing."
And of course, she shares with me the thrill every mother-of-the-bride feels as she watches a daughter marry. She's still fizzing with excitement.
"I always went to weddings and thought: 'Why is the mother-of-the-bride crying?' she tells me. 'But I completely understand why now. It's because it's so amazing to think your daughter is now grown up, leaving home and starting her own life.'
"I'd just sat down in the chapel and everyone saw me go 'Phew' because I'd managed not to slip over in my high heels; then I looked across and saw my sister (Jane) and I watched her face and there were tears — and I'm doing it again, I'm welling up now," she says, dabbing at her eyes with a polka-dot hankie.
Now in her 60th year, her natural Titian red hair is untouched by grey, her stunning legs still slender as a gazelle's — and her endearing eccentricities unstifled by years of inhibiting royal protocol. Sarah Ferguson remains magnificently, unapologetically, herself.
The wedding, on October 12, was a day of extravagant celebration in which every carriage disgorged an eminent guest or a celebrity, and absent loved-ones — prime among them the late Princess Diana — were at the forefront of the Duchess's mind.
"I thought of absent friends and family; of Diana — but she's with me all the time. What I miss most is her tinkling laughter.
"Diana was my best friend and the funniest person I knew. She had such timing and wit. It was a total joy to be with her because we just laughed and enjoyed life so much, and I know she would have loved the wedding."
Heading the panoply of senior royals were the Queen and Duke of Edinburgh, who attends events on a "see how he feels on the day" basis now, and was in close proximity with his former daughter-in-law for the first time in 25 years.
It was said he couldn't stand to be in the same room after Fergie "brought shame" on the Royal Family with those infamous photos of her having her toes sucked by American businessman John Bryan, in the summer of 1992, while separated from Prince Andrew.
But the Duchess's gaze, of course, was fixed firmly on her daughter.
"My proudest moment," she says, 'was watching Eugenie standing tall, very proud to show her scoliosis scar in her low-backed dress. I'd gone to all the fittings and sat there beaming with delight, and because there was no veil it was a very strong statement.
"We rang St George's Chapel to make sure there wasn't a special rule specifying veils must be worn, but there wasn't and Eugenie just wanted to be herself.
"The tiara (borrowed from granny) danced to her. She was just so radiant. She said: 'Mum, I thought I was going to get nerves,' but she didn't.
"She and Jack are just meant to be. He adores her, and now I've got a son. Jack is like Zebedee. Boing, boing!" She demonstrates the energy of the Magic Roundabout character on his coiled spring.
"He will be the best consort there is, as Prince Albert was to Queen Victoria. I know it will be that sort of love match."
There were many private moments in the chapel, the Duchess admits, when her eyes blurred with tears, and there were subtle ways in which she carried the spirit of loved ones with her.
Her father always encouraged her to think of the back-room staff. "He said: 'Remember the kitchen is more important than the dining table' so I made sure the chauffeurs' tent had lots of nice notes, coffees and biscuits, and I put my father's photo up as I knew he'd be saying, 'Well done'."
Major Ronald Ferguson died in 2003 and his first wife Susan — Fergie's mother — was killed in 1998, aged 61, in a car crash in Argentina, where she lived with her second husband, polo player Hector Barrantes.
The vintage Manolo Blahnik bag Fergie held at the wedding belonged to her mother.
"Mum had carried the handbag at my wedding to Prince Andrew and the admission tickets were still in it. They were green — which was why I wore green on the day." And the elderly woman in a wheelchair whom Sarah embraced in the crowd outside the chapel, was her mother's friend, Jessie Huberty.
"I'd gone to live with her in New York for six weeks when I was 19. My father had said, 'You're too spoilt. You have to work your way round America' — so I stayed with Jessie and got a job cleaning lavatories to earn enough to get a Greyhound bus ticket."
Standing near Jessie was Nepalese Sherpa Gyalzen (Sarah also hugged him warmly), with whom she had climbed beyond Everest base camp in 2000 for the MacIntyre charity, which supports people with learning disabilities.
The sherpa, who worked for the Duchess for a few years after this, now lives in New York with his wife and son, and had travelled to Windsor specially to witness Princess Eugenie's big day.
For the party at Royal Lodge on the Saturday, where food was served from a series of stalls, each dish was chosen for its special significance to the newlyweds and their families. There was Argentinean beef — in memory of Susan Barrantes — rice dishes from Nicaragua (where Jack had proposed in front of a volcano), mini hamburgers from the U.S. where Eugenie's employer, art gallery Hauser & Wirth is based.
There was Italian pizza and Spanish paella, while crepes from Switzerland represented Verbier, where the Duke and Duchess jointly own a £13 million chalet.
The couple's friends Ellie Goulding and Robbie Williams — who was there with his wife Ayda Field (their daughter Theodora, six, was a bridesmaid) — both sang their hits. And the Royal Philharmonic Orchestra also performed, its programme including a composition, Twin Flame, by singer-songwriter Tanis Chalopin, written as a wedding present for the couple.
Critics have carped about the extravagance of the wedding — but of course the bride and groom's families met those costs. As is standard at any gathering attended by the Queen, security costs fell to the taxpayer — as they did for Her Majesty's other grandchildren's weddings.
And there in the middle of it all was Fergie, centre stage after years of painful alienation. Today, her rehabilitation seems complete.
For three successive summers she has been to Balmoral; she regularly joins the Queen at Ascot and shares tea with Her Majesty at Windsor. And, of course, all the senior members of the Royal Family (Prince Philip prime among them) mustered for the wedding.
Only Camilla, Duchess of Cornwall, was absent, honouring a long-standing promise to visit a tiny school in Scotland. Was Sarah offended? Not a whit!
"I think it's wonderful she kept to her engagement, especially as it was with children. She's a wonderful lady and was a great friend of my mum," she says magnanimously.
And throughout the vicissitudes of the past two decades, her closeness to the Duke of York has remained unassailable. They share a home — Royal Lodge, Windsor — and have raised their well-adjusted daughters as a partnership.
I ask if she loves him. It seems the Fergie of 2018 has learned diplomacy and deftly side-steps the question, but replies: "We both say it. We are completely compatible. Our bywords are communication, compromise and compassion.
"July 23, 1986 was the happiest day of my life. Andrew is the best man I know. What he does for Britain is incredible; no one knows how hard he works for his country.
"My duty is to him. I am so proud of him. I stand by him and always will. The way we are is our fairy tale.
"Although we are not a couple, we really believe in each other. The Yorks are a united family. We've shown it. You saw it at the wedding.
"We stand up for each other, fight for each other. We're totally respectful of each other's position and thoughts and we listen to each other. Our children listen to us, too.
"And we sit round the table and have afternoon tea together. It's a very important part of our lives."
The question has been raised many times: will they remarry? "So many people have asked me that, but we're so happy with the way we are right now," she says. "We enjoy each other's company; we allow each other to blossom. I know it sounds like a fairy tale but that's the way we are.
"And the Sunday after the wedding, I said to Eugenie and Jack: 'Do you want to stay somewhere special?' No. They wanted to stay at Royal Lodge. So the night before their honeymoon, the whole family were eating pizza together in the kitchen."
On her closeness to the Queen — who reportedly remarked that whatever Fergie has done, she has always been a good mother — she is judicious: "Her Majesty is the finest icon I've ever been lucky enough to share a room with. She's the most exceptional Head of State, lady and mentor. I am very fortunate to know her."
She is equally full of praise for Prince Philip, whom she describes as "an incredible man". "I have huge respect for him and always admired him. It was a lovely photograph of us all together. It was very good to be with him again. My father and he used to play polo together. It brought back memories of that."
It is for being a good mum that Fergie is justifiably celebrated. She says she and her daughters are a "tripod" — an interdependent and solid threesome.
Over the years, the princesses have endured crushing criticism: Beatrice, particularly, has been vilified for her shape, size and dress sense.
The Duchess will not be drawn to comment, other than to say: "I am fiercely protective of my girls. I'm like a lioness."
It's indisputable, too, that the Yorks provide a paradigm on how to parent well after a divorce.
"Of course we're human, both Andrew and I, but when we walked through the door we never brought our adult problems to the children. This is always our rule.
"And you're always honest with your children. When they say, 'Mummy, what's happening?' you say, 'It's interesting you should ask the question,' and you explain in a way they can understand.
"When my parents divorced, I didn't have a parent who was telling me the truth. I found out in 1974 through a newspaper what was happening.
"And I felt … I believed, that I had done something wrong. I think it's really important that children don't feel that. The fact that we divorced had absolutely nothing to do with the girls.
"But I remember thinking I was responsible for my parents splitting up — because I'd cut my hair." She laughs ruefully at the memory. "And because I wasn't good enough. And that was when I began to comfort eat, and why I've had a weight problem all my life.
"It's why I have total empathy with what it is like to be destroyed by self-hatred, because when you comfort eat you put on weight, and then beat yourself up for comfort eating. It is such a vicious circle.
"I comfort-ate all my life from the age of 13. I started when I was at boarding school, when I heard my parents were getting divorced. I got up to 14-and-a-half stone."
Today, she looks enviably slender in a flirty flared skirt teamed with Smythe jacket in racing green. The "soul-destroying" Duchess of Pork jibes that dogged her when she was at her heaviest are now palpably inapplicable.
Her jewellery is trademark Fergie: a gold bracelet bearing her girls' names picked out in diamond-encrusted capitals; a super-sized Remembrance Day poppy blooming from her lapel.
Once she has kicked off the Jimmy Choo heels she wears (at our request) for the photos, she slips, with relief, into flat velvet pumps embroidered with unicorns. They seem to sum up her spirit: fanciful, child-like, princessy. If you asked Fergie her favourite colour, she might well say "glitter".
She seems an amalgam of contradictions: childlike but pragmatic; jolly yet reflective; robust and hearty at times, then fragile.
"It has taken me 59 years, but I'm happy to own this sense of joy I feel now," she says. "My mantra is the Hs: honour, humility, hope and humour. If I have ever let anyone down, and I am sure I have done so at times, I have always tried to amend and do my best. I believe in forgiveness for myself and for others. It's an important quality."
She admits to having felt "sadness" in her past but is careful to distinguish this from depression. When she feels low, she says, she has a strategy for coping. "I take a bit of quiet time; maybe watch a black and white movie and make myself cry even more. (Cary Grant is one of my heroes.) But I love to laugh, too. I find a sense of humour always helps.
"As my grandmother would say, 'This, too, shall pass.' She brought me up to clean my side of the street — by which she meant to forgive and never let the sun go down on an argument."
I ask if she has learnt to cope with the loneliness of successive Christmases spent without her daughters. This year will be the 22nd, since her divorce, that her girls have gone to Sandringham to join the Royal Family, while she, uninvited, will stay home alone.
And once again, Sarah is generous-spirited. "I know that Her Majesty adores my children, so I am happy to share them — both in August and at Christmas."
I ask if it breaks her heart to be a distant observer of this close, familial happiness, but she replies with customary bravado: "No! I am happy making other people happy. I really am like this. I love to share. It's the joy of giving."
She gives a lot of time and energy to her charity work: she is an Ambassador for the British Heart Foundation and is talking to me today to promote the launch of Street Child, newly merged with the charity she set up in 1992, Children In Crisis. She is passionate about the role education plays in lifting people out of destitution. "At Street Child, we all believe that education is a fundamental right and that it is a scandal and a tragedy that there are 121 million school-aged children around the world who are not able to go to school," she says.
Tom Dannant, who established Street Child in 2008, says: "It's a measure of the Duchess's lack of ego that she was prepared to merge her charity with our faster-growing one. She thought it would pack a bigger punch and she could do more to help children that way."
He reports, too, on her passion, stamina and willingness to endure privations. "Earlier this year, we drove through rough, winding roads in Nepal for ten hours, then stayed in a cockroach-infested hotel. She did it to reach the children in greatest need."
I ask Sarah about this trip and she throws up her hands and laughs. "My father would have called it character-building," she says. "They shovelled me in a car and we wanted to find these children who literally had nothing.
"The monsoon rains were coming, they had no food and the water they drank was polluted and infested with cobras. And the hotel was one of those where you sleep on your suitcase because it's more comfortable than the bed."
The charity will be building a school in this remote and impoverished outpost: Sarah has already forged links with some of the children it will educate. "My grandmother always used to say to me: 'If you feel down about life, then go out and give to others'," she recalls.
And there is no doubt in my mind that Sarah's compassion, her empathy — actually her love — for children is genuine. Visiting Julia's House, a children's hospice in Wiltshire with her, she blows in like a gust of fresh air, dispensing sweets and trinkets, joining a craft session, decorating a cake (with unicorns) and reading from one of her Budgie the Helicopter books.
Those who would decry her choice of reading material as opportunistic might do well to recognise that the stipend she received from the Royal Family after her divorce was reputedly just £15,000 a year. She needs to earn money, and does so through a series of creative enterprises.
She shows me her range of teas — ingeniously concocted to smell and taste like the deserts she adores (there's jam roly-poly, chocolate tart, strawberries and cream) — which have helped her resist puddings and keep her weight down. (Some of the profits from sales will go to Street Child.)
She gently cajoles her young audience, remembering their names, chatting on their level.
Later she confides to a group of parents: "I prefer to be with children because I can be with my imagination. What I take away from any visit like this is the kindness, the love, the children and the total joy. I love the atmosphere and goodness here."
I ask if she's looking forward to being a grandmother. She laughs.
"How many children's books have I written? Twenty-two! Frances, I tell you, they'll be older than me at age three! I'll have more fun making the Barbie kit houses than the grandchildren will."
This is, perhaps, the essence of Fergie: to be child-like is to be released from the obligation to conform to adult expectations and conventions. "When I got married people said: 'You mustn't make faces when you go out. You mustn't do this or that.' But I just want to be myself. I'm 59 but I feel about eight years old."
I leave the Duchess freighted with gifts from her. There's a silk scarf (woven by trafficked women), a selection of her tea bags, china wedding mementoes, shortbread — a veritable goodie bag.
As she hugs me, she says, "I like to have harmony. People say it's people pleasing, but it's the way I like to be. It makes me feel good."