Prince William made a devastating promise to his mum Princess Diana just a year before she died.The Prince of Wales, who was just 14 at the time, reportedly vowed to get his adored mum's title back after she was stripped of Her Royal Highness following her divorce from the now King Charles. Diana tied the knot with Charles in 1981 during a fairytale royal wedding at St Paul's Cathedral and she officially became HRH The Princess of Wales.The royal couple went on to welcome their two children, Prince William born on 21 June 1982 and Prince Harry who arrived two years later on 15 September 1984.