Kate Middleton Modified a Key Detail on Her Vintage Dress in Jamaica — Here's Why

Kate Middleton's most vibrant Caribbean tour outfit yet is a vintage find — with a personalized twist.

Arriving for a day of reggae and soccer in Jamaica on Tuesday, Kate and Prince William were greeted with huge cheers by the crowds in Trench Town — with Kate standing out in a bright coral-and-turquoise cotton summer dress from U.K. boutique Willow Hilson Vintage.

"It's a dream come true, and I can't stop beaming," Willow Hilson, the founder of the Cheltenham-based independent boutique, tells PEOPLE. "I've been doing this since I was 21, and all I ever wanted was someone like Kate to wear a dress of mine!"

Hilson bought the 1950s dress from the original owner and describes it as having an "iconic New Look silhouette that cinches in along the waistline and a wonderful wide skirt."

But as worn by the Duchess of Cambridge, the dress is not quite the original design. Kate's style team used a matching shawl that came with the dress to add additional fabric around the neckline.

"Kate doesn't often wear spaghetti straps, so they used the shawl to widen the straps," explains Hilson. "I think it's a great adjustment — it looks amazing on her."

Accessorized with a gold bangle by local Kingston jeweler Lashawndla Bailey-Miller, raffia court shoes by Russell & Bromley and pearl earrings by Copenhagen-born Maria Black, the outfit was a burst of color — perfect for a day that included meeting the Jamaican bobsleigh team and playing the drums at the Trench Town Culture Yard Museum.

"It was so apt, because it's got all the great Caribbean colors, it's such a reggaeton kind of dress in its color palette – she looks like she is having a whale of a time!" says the vintage expert.

It's not the first time Kate has chosen to wear vintage on the couple's ongoing tour of the Caribbean. Departing Belize on Tuesday, Kate teamed a white pair of trousers with a red vintage Yves Saint Laurent jacket that had been in her closet for more than two decades — she bought it while studying at St. Andrews, where she and William met.

"Sustainability in fashion is a big conversation right now," says Hilson, who opened her original boutique in 2012 before moving to Cheltenham in 2019. " I hope it will be ongoing. I think getting someone like Kate on board with that is really good, because it shows people that it's okay to wear second hand and it's okay to wear vintage."

Although Kate has recycled (and on occasion upcycled!) her outfits for many years, it's the first time she has worn vintage looks in such quick succession. It's also the first time she has worn an outfit from the 1950s. (She wore a pink-and-black polka dot vintage Oscar de la Renta dress in 2020 that is believed to be from a more recent era.)

However, it's not unprecedented for Kate's in-house team to modify an outfit to make it more "tour-appropriate." For the royal couple's tour of India and Bhutan in 2016,Kate Middleton, Meghan Markle and more!"> Kate wore a maxi dress by Mumbai designer Anita Dongre, personalizing it by turning the scarf into a belt to make the look more contemporary and casual.

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Hilson, who has been inundated with calls from around the world since Kate wore her vintage find, says she couldn't be happier that the dress found such a high-profile home: "I think every vintage shop owner dreams of someone like Kate Middleton wearing one of their dresses. It's quite unexpected but just amazing."