LONDON, ENGLAND - FEBRUARY 09: A Catherine Walker dress that was worn by Princess Diana is displayed at the Fashion Rules Exhibition at Kensington Palace on February 9, 2016 in London, England. The exhibition, that re-opens to the public on February 11, contains pieces including the dress Queen Elizabeth II wore for her official Silver Jubilee photograph and a dress worn by Diana, Princess of Wales for her last official photo shoot with famed photographer Mario Testino. (Photo by Ben Pruchnie/Getty Images)