LONDON, UNITED KINGDOM - DECEMBER 18: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) A police officer on gate duty at Buckingham Palace looks at a 'Royal Families' crib sheet before members of the Royal Family arrive to attend a Christmas Lunch hosted by Queen Elizabeth II on December 18, 2013 in London, England. (Photo by Max Mumby/Indigo/Getty Images)
