Celebrity Kate Middleton Kate Middleton Has Been Following This Casual Fashion Rule Since Before She Was a Royal Hey, when it works, it works. By Samantha Sutton Samantha Sutton Instagram Samantha is InStyle's senior fashion editor. She joined the brand in 2019 and oversees the site's fashion coverage, including trend reporting, fashion exclusives, celebrity style interviews, and Fashion Week coverage. InStyle's editorial guidelines Published on August 7, 2020 @ 11:20AM Pin Share Tweet Email Photo: Getty Images/InStyle.com It's admittedly taken some convincing to welcome certain '90s and '00s trends back into our wardrobe. But, while items such as vests and low-rise jeans still feel questionable, we have hung onto a few key pieces from way back when — and, so it seems, has Kate Middleton. Striped shirts, for instance, were a must-have for the royal back in 2007, long before she and Prince William ever said "I do." Now, over 13 years later, she continues to work them into her outfits, stepping out in the wardrobe staple every few months. 10 Fashion Items You Thought Were Out, But Are Suddenly In Again It's easy to see why Kate gravitates towards this simple style: it's timeless and easy to dress both up and down. Striped shirts have definitely become a go-to and rule of sorts for the duchess. Whenever she's having a laid-back, casual day, her outfit tends to consists of a navy and white option, which she pairs with jeans and a crisp pair of white sneakers. Still, there have been numerous ways Kate has worn striped shirts over the years. Take a look at some of her best outfits, ahead. 2007 Mark Milan/FilmMagic While out in London, Kate wore a very aughts combo of a simple striped tank top, black skinny jeans, a chunky belt, and some wedges. 2007 Indigo/Getty Images This shirt style also happens to be Kate's choice for a variety of activities. She chose to wear a striped tee and leggings while taking part in a training session with the Sisterhood cross-channel rowing team. 2012 Pascal Le Segretain/Getty Images After Kate officially became the Duchess of Cambridge, she was still loving this classic style. At the 2012 Olympics in London, she layered a striped sweater under a navy blazer, completing her outfit with skinny jeans and those signature wedges. 2013 Max Mumby/Indigo/Getty Images When it works, it works! Kate pretty much repeated that same outfit a year later, while attending a SportsAid Athlete Workshop. 2014 Anwar Hussein/WireImage Kate didn't bother with skirt suits and heels while watching a charity polo match. Instead, it was a long-sleeved striped tee to the rescue, styled with jeans and flats. 2015 Max Mumby/Indigo/Getty Images Kate sure loves the navy and white combo, but sometimes she switches up the shade, opting for a royal blue. 2015 Karwai Tang/WireImage She may be wearing layers, but Kate's striped shirt still peeked out as she attended the America's Cup World Series. 2017 CHRIS JACKSON/AFP via Getty Images A splash of red made Kate's simple outfit all the more eye-catching as she hosted a reception ahead of the London Marathon. The One Accessory Both Amal Clooney and Kate Middleton Wear on Repeat 2017 DMC/GC Images We wouldn't be surprised if Kate's closet was full of long-sleeved striped tees in all sorts of colors. While visiting Germany, the royal made sure to pack a light blue option. 2019 Mark Cuthbert/UK Press via Getty Images Of course, the duchess doesn't always dress down her striped shirts. While launching the King's Cup Regatta, she chose to style a sweater version with wide-leg navy pants and heels. So simple yet so sleek. 2019 Antony Jones/Getty Images The same bottoms made an appearance a few months later, but Kate switched up her top. She went a little more modern with a multi-colored, ruffled and peplum design, but gave things a casual twist with white sneakers.