While her necklace has wowed on many occasions, the Duchess added to her growing collection of Jenny Packham gowns with a new style - this time opting for a V-neck ink blue silk tulle dress which showed off her sunkissed skin from a recent winter holiday with Prince William and Prince George in Mustique. She pared the dress with a pair of black high stiletto court shoes.
The floor-sweeping gown is more timeless than other looks we have seen from Catherine in recent years. Is the Queen's stylist already hard at work?
Once inside, Catherine toured the mystery portraits in the new exhibition. She stopped for a while in front of a sketch of Diana, Princess of Wales while chatting to Grayson Perry, who has refused to let slip which portrait is his work.
The gala was the start of a busy week for the Duchess. She is due to attend Northolt High School in Ealing on Friday to open a new art room.