Royals Kate Middleton and Prince William Glam Up Glasgow in Complementary Regal Blue The couple joined Prince Charles and Camilla, Duchess of Cornwall at the U.N. COP26 climate summit as Queen Elizabeth stayed back at Windsor Castle to rest, per doctor's orders By Stephanie Petit Stephanie Petit Stephanie Petit is a Royals Writer and Reporter at PEOPLE. People Editorial Guidelines Published on November 1, 2021 02:39 PM Share Tweet Pin Email Photo: DANIEL LEAL-OLIVAS/POOL/AFP via Getty Kate Middleton and Prince William stepped out in Glasgow on Monday evening — wearing royal blue, times two! They teamed up with Prince Charles and Camilla, Duchess of Cornwall to represent the royal family at the 2021 United Nations Climate Change Conference in Scotland. After an afternoon outing with young scouts when they grilled up veggie burgers, made and scattered wildflower seed 'bombs,' and mastered the basics of bicycle maintenance, Kate and Prince William had an outfit change before joining Prince Charles to host a reception for key members of the Sustainable Markets Initiative as well as winners and finalists of the first Earthshot Prize Awards. Kate Middleton and Prince William Grill Veggie Burgers and Sow Wildflower Seeds in Eco-Friendly Scout Meet-Up Prince William and Kate Middleton. DANIEL LEAL-OLIVAS/POOL/AFP via Getty The Duchess of Cambridge opted for a dazzling cobalt coat dress by Eponine with Rupert Sanderson heels and blue topaz earrings by Kiki McDonough, while the Duke sported a navy suit, white dress shirt and blue patterned tie as he continued to wear the poppy pin he wore earlier in the day to honor veterans ahead of Remembrance Sunday on November 14. The two couples reunited at an evening reception to mark the opening day of COP26, with the Duchess of Cornwall wearing a teal Bruce Oldfield dress featuring buttons recycled from another outfit. Kate Middleton. DANIEL LEAL-OLIVAS/POOL/AFP via Getty Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! Queen Elizabeth addressed the assembled delegates via a recorded message as part of the reception, noting that climate change was a "subject close to the heart of my dear, late husband, Prince Philip, the Duke of Edinburgh." Sharing a memory from the start of Philip's half-a-century-long campaign to fight climate change, she urged, "If we fail to cope with this challenge, all the other problems will pale into insignificance." She continued, "It is a source of great pride to me that the leading role my husband played in encouraging people to protect our fragile planet lives on through the work of our eldest son, Charles, and his eldest son, William. I could not be more proud of them." "Of course, the benefits of such actions will not be there to enjoy for all of us here today: we none of us will live forever," she also noted. "But we are doing this not for ourselves but for our children and our children's children, and those who will follow in their footsteps." The monarch, 95, announced last week that she "regretfully" decided not to attend the conference after being advised by doctors to rest. After an overnight hospitalization on October 20, Buckingham Palace announced Friday that the monarch has been "advised that she should continue to rest for at least the next two weeks." She was spotted driving solo around the grounds of Windsor Castle on Monday. The Queen plans to the National Service of Remembrance in a few weeks and will continue to undertake light duties from Windsor Castle.