The Duke of Edinburgh was Colonel-in-Chief since 2007.
He had been connected to all Regiments since its formation.
Camilla and Sophie were joined by the Duke of Kent and the Duke and Duchess of Gloucester, the Queen’s cousins.
The last time royal fans saw the Duchess of Cornwall was earlier this week while attending the Prince’s Countryside Fund Raceday at Ascot where she donned an all-brown outfit.
The Duchess wore a chic tweed coat and fluffy hat.