Her Royal Highness looked elegant in a navy and white polka dot midi-dress, paired with comfortable $275 Sole Bliss Ingrid heels.
The future Queen consort styled her platinum locks in her trademark blow dry and added a touch of glamour with a stack of pearls round her neck.
Later on Thursday, the Duchess unveiled a plaque marking the opening of RAF Halton's new Youth Activities Centre.
It's been a busy few weeks for Camilla and Charles, who started the month with a five-day tour of the Welsh region to celebrate Charles' 50th investiture as Prince of Wales.
The royal couple returned to London to attend the private ceremony for Prince Harry and Meghan Markle's son Archie's christening at Windsor Castle on July 6.
Just 25 people were invited to the intimate event, with Queen Elizabeth II and Prince Philip unable to attend due to prior commitments for the Queen in Scotland.
On Tuesday, Camilla hosted a reception for Ebony Horse Club in the garden of Clarence House, where she fed an adorable 10-year-old Cob horse called Splash.