LONDON, UNITED KINGDOM - DECEMBER 17: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge attend a Christmas lunch for members of the Royal Family hosted by Queen Elizabeth II at Buckingham Palace on December 17, 2014 in London, England. (Photo by Max Mumby/Indigo/Getty Images)