WINDSOR, ENGLAND - JUNE 18: Camilla, Duchess of Cornwall (L), Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge leave the annual Order of the Garter Service at St George's Chapel, Windsor Castle on June 18, 2011 in Windsor, England. The Order of the Garter is the senior and oldest British Order of Chivalry, founded by Edward III in 1348. Membership in the order is limited to the sovereign, the Prince of Wales, and no more than twenty-four members. (Photo by David Bebber - WPA Pool/Getty Images)