To mark Mother’s Day, Prince Harry arranged for flowers to be placed on Princess Diana’s grave. Now living Stateside, the royal had flowers laid out on his behalf at her gravesite in Althorp Park. Harry was just 12 years old when his mother died in a fatal car accident in 1997. To mark Mother’s Day, Prince Harry arranged for flowers to be placed on Princess Diana’s grave. Pic: Georges De Keerle/Getty Images His older brother Prince William also paid tribute to this mother with the Kensington Palace official Instagram account sharing cards to Diana from her grandchildren.