Princess Diana married King Charles on July 29, 1981, at St. Paul's Cathedral in London . Almost three decades earlier—on April 19, 1956— Grace Kelly had wed Rainier III, Prince of Monaco , meaning she was perfectly placed to advise Charles's bride . Princess Diana's former butler , Paul Burrell , opened up about Princess Grace 's alleged interaction with Diana on the eve of her wedding to Charles in the book A Royal Duty . "I have never seen such a beauty as Princess Grace," Burrell wrote. "That evening she even outshone the bride-to-be, and her tiara was every bit as magnificent as The Queen's. Lady Diana was captivated." According to Burrell, Diana and Grace "struck up an immediate rapport," which led to them becoming "locked in conversation." Essentially, the former actress quickly became a "role model and inspirational figure" to the young Diana, the ex-butler shared. The fact that Grace had been "an outsider...who had married into royalty" only endeared her further to Diana.…