Royals Prince William Wears Velvet and Feathers for One of the Fanciest Days on the Royal Calendar! The royals don't do summer casual By Simon Perry Published on June 18, 2018 10:20 AM Share Tweet Pin Email Royals don’t do summer casual — at least not when they’re on duty. On Monday, Prince William wore a traditional velvet robe and hat (complete with ostrich feathers!) for Garter Day, which celebrates the oldest and most senior order of knighthood in the U.K. William, 35, took part in the Order of the Garter parade and service at St. George’s Chapel, Windsor — the scene of the magnificent wedding of Prince Harry and Meghan Markle on May 19. William, his father Prince Charles, 69, and other senior royals joined Queen Elizabeth for the service, which last took place in 2016. Last year the service was canceled when the date of the State Opening of Parliament suddenly moved following a surprise general election. Matt Dunham/AP/REX/Shutterstock Chris Jackson/Getty Images Ian Vogler/WPA Pool/Getty Kate Middleton, who is on maternity leave since giving birth to Prince Louis in April, was not at the annual event. Can’t get enough of PEOPLE’s Royals coverage? Sign up for our newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! William proceeded down from the castle alongside his father. The Queen, who was without Prince Philip this year (he retired from his official royal duties last summer), arrived by car. William was made a member of the order in 2008, two years before he got engaged to Kate Middleton. After the half-hour service in the chapel, William joined the other royals, including Camilla, Duchess of Cornwall, in a carriage procession back up to the castle’s state apartments. Tim Rooke/REX/Shutterstock Chris Jackson/WPA Pool/Getty Tim Rooke/REX/Shutterstock RELATED VIDEO: Prince William Is Making Royal History with His First Official Visit to Israel Garter Day begins a week of festivities at Windsor, where the Queen is based as she heads to Royal Ascot horse racing on Tuesday and through the rest of the week. Not present at the service: Harry and Meghan. Harry has sometimes attended to watch the proceedings but is not a Garter knight.