Despite arguably being the most powerful woman inside the monarchy, apart from Her Majesty, Kate remains adorably unsure of herself. Photo / Dean Purcell
She has long been the royal that we see, but rarely hear. Yet in a surprisingly candid collaboration with former Great British Bake Off judge Mary Berry, the Duchess of Cambridge has revealed a little more of herself as she prepares to become the next Princess of Wales.
During the hour-long documentary, A Berry Royal Christmas, (screened in Britain Monday night), Kate lifted the lid on life behind the gates of Kensington Palace, telling the 84-year-old cookery queen about Prince Louis's love of home-grown beetroot, and how she once forgot to put the lid on the blender - with disastrous results.
So what has prompted one of the House of Windsor's most reticent members to suddenly give an unprecedented interview? And what does it tell us about her?
It is somewhat ironic that Berry admitted to suffering from nerves before meeting Kate, when anyone close to the Duchess will tell you that she herself gets very anxious before any public-speaking engagement.
Unlike her sister-in-law, the Duchess of Sussex, to whom off-the-cuff speeches seem to come naturally, the former Marlborough schoolgirl has never been particularly comfortable in the spotlight, despite her status as one of the most famous and most photographed women in the world.
Yet in her chatty and refreshingly open exchanges with the baking guru, the Duchess showed how much she has quietly grown in confidence since she hesitatingly uttered her wedding vows before a global audience of billions, in April 2011.
When she started out as a full-time working royal, Kate was noticeably shy and awkward when she was required to take to the stage; at times actively avoiding the opportunity.
But now, in early years support, she has found a cause close to her heart, and there is a sense that the characteristically introverted Duchess is finally willing to show off what she has been working on.
That much was clear from last night's prime-time appearance on BBC One, in which she casually intermingled chat about family life with her charitable work.
In a rare glimpse into her role as a royal mother, the 37-year-old gave Berry a tour of her new play garden at RHS Wisley, and spoke about how much her children love being outside, as well as her quest to encourage families to spend more time together.
Echoing the feelings of parents across the land, the mother-of-three admitted: "Sometimes, when it's chucking it down with rain and it's freezing cold and I'm dragging [the children] outside, they would probably rather be staying inside. But I think it's so important."
Describing how the Queen's great-grandchildren have proudly filled the garden with "crazy little" items they have collected, she added, touchingly: "George thinks it's a museum. It's very sweet. It's quite small, it's full of these little treasures, whether it's a crab's claw or a little shell he's found that he loves.
"And that's what's so nice - for them, their world's quite small."
The landscape of Kate's world, however, is growing ever-larger as she takes on more responsibilities - often keeping the Queen company at official engagements - and adapts to what will eventually be an unavoidably public-facing role.
Her increasing willingness to divulge tidbits about her private life is proving that the shy royal is determined to find her feet sooner rather than later.
That's not to say that the prospect of being a future Queen has gone to her head - quite the opposite, in fact.
Despite arguably being the most powerful woman inside the monarchy, apart from Her Majesty, as the wife and mother of a future king, Kate remains adorably unsure of herself.
A royal insider confided how apprehensive she was before speaking to the BBC's Monty Don about her Back To Nature Garden during the Chelsea Flower Show in May this year.
"She was visibly nervous before the interview," revealed the source. "It was quite charming really. You would have thought she was going before Jeremy Paxman. You could tell she felt under enormous pressure not to slip up."
Seemingly much more at ease with Berry, of whom she is a self-confessed fan, the Duchess's revelation that the couple's large, modern kitchen at Kensington Palace is at the heart of family life, painted the picture of a hands-on woman trying to give her children as normal an upbringing as possible.
Describing how she enjoys cooking with George, Charlotte and Louis, and encourages them to be as creative and independent as possible, it seemed Kate was feeding off her own childhood, when her parents' party and decorations supplies business, Party Pieces, saw Kate and her siblings, Pippa and James, co-opted into cake-tasting sessions.
Reassuringly frank and self-deprecating, there is no reason to disbelieve her when she reveals that she is just like any other parent, and can find herself awake in the small hours, trying to create impressive bakes.
"It's become a bit of a tradition that I stay up until midnight with ridiculous amounts of cake mix and icing," she said. "I make far too much but I love it."
Berry also joined the Duchess on a trip to Liverpool to visit the Brink, the UK's first "dry bar", set up by Action on Addiction.
As they blended mocktails behind the bar, the Duchess admitted she had once suffered an unfortunate mishap with a blender.
"I did this with a spinach soup once, and forgot to put the lid on it," she said. "We ended up with spinach soup on the ceiling."
How refreshing to hear that someone so immaculately turned out and famed for "never putting a foot wrong" has endured the same sort of kitchen nightmares as the rest of us.
If it had been any other celebrity mother revealing they had made Berry's pizza dough with their children - who not only grow their own vegetables but actually enjoy eating carrots and beans - Twitter would have been awash with #mumupmanship hashtags.
But gentle confessions like the blender moment, and the revelation that she was a "terrible" waitress during her university days, will endear Kate even more to the public.
As will her honesty about her charity work, which she admitted often has a profound personal effect, and that it's not always easy to switch off and return to her own life.
"You've taken on so many interesting stories - quite traumatic stories - and you have to allow yourself time to reflect and really take on what you've learnt before you dive into your own life and school pick-ups," she explained.
This wasn't an over-privileged pampered mother speaking, but someone who clearly wants her charitable work to be as impactful as possible.
Arguably the most penetrating disclosure came when Prince William admitted it was his wife who was the mastermind behind the Heads Together mental health campaign, spearheaded by the younger royals at Kensington Palace.
"She realised that my work, Harry's work and her work were all headed in different directions, but all dealing with mental health," he told Berry.
"She was the one who joined the dots and said we needed to tackle mental health."
How fitting that the woman who has every reason to show off, but chooses not to, should have kept her pivotal role in the most successful royal initiative in recent memory such a closely guarded secret.