Yet Catherine, Princess of Wales, wore an elegant cream-colored look to a wedding on Saturday with little fanfare.

Prince William and Kate Middleton attended Peter Phillips and Harriet Sperling’s wedding on Saturday, but the royal guest list was not the only part of the day that drew attention.

Many of the most prominent names of the British royal family were in attendance to bear witness to the union, including King Charles III and his wife Queen Camilla, as well as heir apparent Prince Wil...