If you thought Prince Louis stealing a sceptre at King Charles’s coronation was peak royal mischief, think again. The crown’s latest agents of adorable anarchy? Princess Charlotte, 10, and her 11-year-old cousin Mia Tindall – the self-proclaimed “Double Trouble” who’ve turned family gatherings into giggle-fests and nannies into nervous wrecks.

According to royal expert Ingrid Seward, editor-in-chief of Majesty magazine, the two girls are inseparable troublemakers whose combined energy could power the Changing of the Guard. “When the cheeky pair are together, that’s it – they become as one,” Seward revealed in a chat with The Sun’s Fabulous magazine. “Charlotte’s super responsible for her brothers, bossing them around like a mini Kate Middleton. But with Mia? It’s game on. They’re total opposites, but they egg each other on until the whole room’s in stitches.”

The duo’s legend kicked off in earnest at Queen Elizabeth’s Platinum Jubilee in June 2022, when eagle-eyed viewers spotted Charlotte and Mia hanging precariously out a Buckingham Palace window, necks craned like meerkats to catch a glimpse of the Trooping the Colour flypast. Prince George and Louis were right there with them, but it was the girls’ conspiratorial whispers and barely contained squeals that stole the show. “Investigating the festivities,” palace insiders joked later. “Or plotting world domination – hard to tell.”

Fast-forward to Christmas Day 2023 on the windswept lawns of Sandringham Estate, and the evidence mounted. As the royal family trudged to St. Mary Magdalene Church in their signature somber procession – King Charles in tweed, Camilla in camel coat, the Waleses bundled against the Norfolk chill – Charlotte and Mia lagged behind, locked in a fit of hushed hysterics. Lip-readers (because of course there are royal lip-readers) swear Mia whispered something about “Granny’s hat looking like a wonky teapot,” sending Charlotte into a shoulder-shaking spasm of laughter she tried (and failed) to hide behind her mittens.

It was the kind of unfiltered joy that had even the steeliest corgi trailing behind wagging its tail extra hard.

But the real spark for their “Double Trouble” moniker? A top-secret prank at last month’s pre-Christmas tea at Windsor Castle that’s still got courtiers chuckling – and one hapless footman blushing.

Picture this: the Long Gallery, fairy lights twinkling off ancestral portraits, silver trays groaning under scones and clotted cream. The children’s table is a powder keg of potential chaos – George politely nibbling cucumber sandwiches, Louis eyeing the jam with predatory focus. Enter Charlotte and Mia, who’d slipped away from the “grown-up” chatter under the guise of “fetching more biscuits.”

Ten minutes later, pandemonium. The footman serving the adults returned to find every single teacup swapped: the King’s Earl Grey now brimming with what looked like chocolate milkshake (it was just very diluted cocoa, but the foam was suspiciously Santa-hat shaped). Camilla’s Darjeeling? Laced with a “special herbal infusion” that turned out to be Mia’s pilfered packet of gummy bear-flavored tea from the gift shop. And poor Prince Edward? His cup had a tiny paper sailboat floating in it, complete with toothpick mast and napkin sails reading “Ahoy, Uncle Eddy!”

The girls? Nowhere to be seen. Until dessert, when they reappeared with innocent smiles, Charlotte offering Charles a “peace cookie” shaped like a crown (with one strategically placed raisin for the jewel). The monarch, mid-sip of his faux milkshake, paused – then let out a belly laugh so rare it echoed off the tapestries. “Double Trouble strikes again,” he reportedly quipped, ruffling Mia’s curls. “Reminds me of your mother and Aunt Anne in the ’70s.”

That’s high praise from a man who once hid fireworks in his sister’s pony saddle as a teen.

The friendship isn’t just fireworks; it’s fireworks with heart. Charlotte, the poised middle child of William and Kate, is often the family’s pint-sized enforcer – shushing Louis during balcony waves, straightening George’s tie before photos, channeling her mother’s no-nonsense elegance at age 10. But around Mia, that armor cracks. “She lets her hair down – literally,” a Lambrook School parent whispered at a recent PTA coffee. “They’ve got this secret handshake involving jazz hands and a curtsy. Teachers pretend not to notice.”

Mia Grace Tindall, born in 2014 just months after Charlotte, is the wild card. Daughter of Zara Tindall (née Phillips, the Queen’s equestrian granddaughter) and former rugby hunk Mike Tindall, Mia’s got that free-spirited Gloucestershire grit. No titles for her brood, insists Zara – just muddy wellies, rugby scrums in the garden, and zero tolerance for stuffy protocol. “We want shrieking giggles and play fights,” Mike once told The Times. “If they come home filthy, we’ve done our job.”

The girls attend different schools – Charlotte at the ultra-private Lambrook in Berkshire, Mia at a cozy prep in the Cotswolds – but weekends and holidays are their playground. Royal fly-ons-the-wall say they’ve turned the Windsor Farm Shop into a covert ops base, “borrowing” eggs for “experiments” (one ended with a meringue bomb in the dairy aisle) and staging epic hide-and-seek across the 655-acre Great Park, once roping in actual park rangers as unwilling search parties.

Their bond echoes a deeper royal rhythm: cousins as lifelines. Think young William and Zara, partners in palace pranks who’d sneak extra biscuits from the kitchens and stage mock polo matches on the lawns. Or Harry and Eugenie, trading secrets in the nursery while the world watched their parents’ dramas unfold. “It’s how the Firm survives,” Seward notes. “These kids remind us the crown isn’t all duty – it’s double trouble with a side of heart.”

Of course, not every caper ends in applause. Last Easter at St. George’s Chapel, Charlotte and Mia’s attempt to “enhance” the flower arrangements with hidden whoopee cushions (sourced from a Windsor joke shop) led to a muffled pffft during the hymns that had the Archbishop stifling a snort. Kate swooped in with the mom-glare-of-death, but later, over tea, she was overheard telling William, “They’re keeping us on our toes. Just like you and Fergie used to.”

Zara, ever the cool aunt, posted a cryptic Instagram story post-Jubilee: a blurry snap of two pairs of wellies caked in mud, captioned “Cousins: because siblings are so last century. #DoubleTrouble.” It racked up 2.7 million likes, with fans dubbing the duo #MiniMeghans (for the mischief) and #FutureQueens (for the charm).

As Charlotte blew out her 10 candles earlier this month – chocolate cake smuggled from the kitchens, naturally – insiders say Mia was the first to FaceTime, belting out “Happy Birthday” off-key while waving a handmade card covered in doodled crowns and confetti explosions. “To my partner in crime,” it read. “May all our pranks be epic.”

With Mia turning 11 in January, the stakes are rising. Whispers from Sandringham suggest they’re already scouting “targets” for the 2026 Commonwealth Games: think swapped national flags or a corgi conga line during the opening ceremony.

King Charles, who’s weathered his share of Windsor whirlwinds, couldn’t be more delighted. “They’re the spark we need,” he told a guest at a recent garden party. “In a world of stiff upper lips, these two are all lower lip giggles.”

So here’s to Charlotte and Mia – the cheeky cousins proving that even in the shadow of sceptres, the best royals are the ones who know when to curtsy… and when to cushion-bomb.

Double Trouble isn’t a warning.

It’s a promise.

And the palace? It’s never been more alive.