Prince George, Prince Louis and Princess Charlotte.Photo: Karwai Tang/WireImage

King Charles’coronationday is almost here — and the royal children will no doubt be dressed to impress.
Speaking exclusively with PEOPLE, British childrenswear designerRachel Riley— one of whose designsPrincess Charlottewore Wednesdayat the Westminster Abbey coronation rehearsal— says of the 8-year-old princess and her brothers, Prince George andPrince Louis, “Everyone is going to be dressed in a very formal way because it is their grandfather’s coronation; it is such a momentous occasion.”
As the oldest (and future monarch), “big boy"Prince George, 9, will likely “have a formal outfit that’s been made specially for him.”
And the youngest of the three, 5-year-oldPrince Louis, “has always been full of character — he looks like he’s a bundle of fun!”
“It’s quite interesting the wayeach of the royal childrenare quite different,” Riley says. “Prince Georgeis the future king; he’s the big boy, and he’s at the age where he’s now wearing suits.Princess Charlottewill be wearing a lovely dress, I’m sure, andPrince Louis, as the youngest, he still gets to wear short trousers, and we’ll see more of the cute factor.”
Kate Middleton and Princess Charlotte.Samir Hussein/WireImage

Of theBlossom Button Front dressPrincess Charlottewore from Riley’s line to the coronation rehearsal at Westminster Abbey on Wednesday, the designer says, “She’s 8, and she looks gorgeous and at ease, but she also wore the same dress when she was 4 in a different print.”
Charlotte has worn Riley’sBlossom Button Front Dressthree times in public in different prints, whilePrince Georgehas worn nine of the designer’s outfits for public appearances over the years, beginning when he was very young.
Riley notes that, in her opinion, “the public interest in what a real-life prince and princess wears is incredible,” adding, “These images will be in the history books, and that’s what’s so delightful when they wear our designs.”
“They love traditional clothes, and it’s lovely tosee them wearing things againand again,” she continues of the royal siblings.
RELATED VIDEO:Prince George,Princess CharlotteandPrince LouisJoin Kate andPrince Williamat Coronation Rehearsal
She also stresses that her designs are meant to make children “feel good” and be “comfortable,” as opposed to something stuffy and just for show.
As for Wednesday’s practice for Saturday’s coronation, “Princess Charlottewas thinking about her rehearsal today, not thinking about her dress, and that’s my aim,” she explains.
Kate Middleton, Princess Charlotte and Prince William.Joe Giddens/PA Images via Getty

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Riley is excited to see how the “lovely event to celebrate” will all play out, noting thatthe crowning of King Charles, 74, is “bringing everyone together.”
“It will be lovely to see all three of them at such a historic occasion,” she tells PEOPLE ofPrince WilliamandKate Middleton’s children. “It is what Britain does best in terms of the pageantry involved.”

Riley calls dressing the royal children “such an honor” and “one of my proudest moments” over the course of her label’s25-plus-years in business.
“It just never loses the excitement or sparkle. I’m always so delighted,” she says. “To be part of so many people’s family moments, it’s a great treat.”
And while “it’s always fun to dress all children,” Riley reveals to PEOPLE that “what’s particularly rewarding as a designer and a business owneris that the royal children wearour clothing and they seem comfortable in them.”
“I could never have dreamt — when I set up my business 25 years ago, when my kids were small and I wanted to make beautiful things for them — I could never imagine, in my wildest dreams, that one day the royals would be wearing my outfits,” she adds.
“It really is an honor,” Riley says.
source: people.com