Kate Sparkles at the Earthshot Prize Awards

The couple walked the green carpet at London’s Alexandra Palace for the event. The Duke and the couple’s Royal Foundation launched the prize initiative in 2020, calling it “the most prestigious global prize for the environment in history.” The Royal Foundation website notes that they hope the prize “will incentivise change and help to repair our planet over the next ten years – a critical decade for the Earth.”

Appropriately, William wore a jacket made of dark green velvet for the ceremony, while Kate reached into her collection to bring back a favorite dress from the early days of the couple’s marriage. This lavender Alexander McQueen gown has been in her closet for more than a decade. Those attending the ceremony were reportedly asked to “consider the environment” and not to buy new clothing to wear to the event.

Here’s a glimpse of the last time we saw the Duchess wear this particular Alexander McQueen gown in public. In July 2011, she wore the dress in Los Angeles for a BAFTA Brits To Watch Event. You’ll note that she wore a different belt with the gown on that occasion.

During the previous Los Angeles outing for the gown, Kate paired the dress with the Queen’s Diamond Chandelier Earrings. This time around, she wore a pair of earrings that have been in her jewelry box for five years.

She chose a pair of earrings from her collection of Kiki McDonough pieces. These earrings, first worn at the wedding of her sister, Pippa Middleton Matthews, in 2017 (pictured above), are set with diamonds and morganites.

We got another good view of the earrings inside Alexandra Palace, as Kate chatted with Sir David Attenborough.

Kate also made an appearance during the televised ceremony, handing out one of the evening’s awards. Five winners were honored with £1 million prizes to acknowledge their important work and allow them to pursue solutions to the world’s greatest environmental problems.

Kate got a few tips on presenting from a professional—Dame Emma Thompson—before stepping out on stage. Dame Emma took the dress requirement seriously as well, wearing the same trouser suit that she wore to receive her damehood from Prince William back in 2018. (You can’t see it in this image, but she’s also got the star of the Order of the British Empire pinned to her lapel.)

Kate announced the winner of the inaugural the Protect and Restore Nature. The prize went to the Republic of Costa Rica, which has made huge strides in restoring its forests. The million-pound prize will help the nation in a new project, which compensates local citizens who work to restore natural ecosystems. (You can read a full list of the prizes and the winning projects here.)

Both William and Kate spoke during the ceremony, and they watched proudly from the audience as others handed out awards and spoke about the Earthshot initiative. In a message played during the broadcast, William noted that the next decade is a crucial tipping point for the planet: “Time is running out. A decade doesn’t seem long enough, but humankind has an outstanding record of being able to solve the unsolvable.” His Earthshot Prize will continue to reward those who develop visionary solutions in the fight against climate change. William announced that next year’s awards ceremony will be held in the United States.