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It was an act of gallantry he repeated later that evening while attending a glamorous state dinner with the Duchess of Cornwall, held in their honour at Madrid's Royal Palace.
The event proved to be a glittering affair as the wives of Britain and Spain's future monarchs donned their finery for the occasion.
Camilla looked radiant in a blue Bruce Oldfield silk gown and diamond earrings and necklace from her private collection.
Her counterpart, 37, chose a striking scarlet Felipe Verela gown, also accessorised with diamonds.
The royal quartet and VIP guests feasted on a banquet including an entree of Spanish ham, artichoke and leek, followed by hake and, to finish, hojaldre – a dessert made from cream, fruit and pastry.
Both Felipe, 43, and Charles then each addressed the room, which included the Duchess of Alba, one of the country's best known aristocrats.
The 85-year-old holds more titles than any other noble, including Queen Elizabeth II, and is said to be able to travel across the country without leaving her estates.
On Thursday, Charles and Camilla were due to have lunch with King Juan Carlos and Queen Sofia at their residence, Zarzuela Palace, before moving on to the southern city of Seville on Friday.