Kate, 30, decorated her blue ensemble by Rebecca Taylor with a simple $40 enamel brooch in the shape of a poppy, the red flower symbol of the Royal British Legion charity.
Dubbed “poppy bling” by a Legion spokesman, the brooches are for sale online at Poppyshop.org.uk.
Kate and William were at Goldsmith’s Hall in London to mark the achievements of a group of servicemen who recreated the Scott-Amundsen race to the South Pole.
Next, the couple is expected at the Imperial War Museum Foundation for an event to raise money to build new World War I galleries at the museum. It will be the second outing for the couple in as many days.
On Wednesday night, the pair attended the U.K premiere of the movie African Cats.