LONDON, UNITED KINGDOM - JUNE 18: Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall attend a commemoration service to mark the 200th Anniversary of the Battle of Waterloo, at St Paul's Cathedral on June 18, 2015 in London, England. (Photo by Anthony Devlin - WPA Pool/Getty Images)

LONDON, UNITED KINGDOM - JUNE 18: Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall attend a commemoration service to mark the 200th Anniversary of the Battle of Waterloo, at St Paul's Cathedral on June 18, 2015 in London, England. (Photo by Anthony Devlin - WPA Pool/Getty Images)