Prince Charles has not visited the grave of his ex-wife, Princess Diana, since her fatal car crash nearly four years ago, her brother, Charles (Earl) Spencer, has charged. “Prince Charles has an open invitation to the memorial,” Spencer, 37, reportedly told BBC Radio, “but as yet he has not taken up the invitation.” Unlike their father, Princes William and Harry have made regular pilgrimages to their mother’s final resting place on the Spencer family estate, Althorp. Spencer offered no explanation for Charles’s absence, however. “It may be that he sees her as an ex-wife.” Spencer took aim at the Royal Family during Diana’s funeral, making pointed reference to its less-than-loving treatment of Diana. Spencer’s remarks were made with the entire Royal Family in attendance. In his latest observations on the House of Windsor, Spencer, focusing on Charles, said that his former brother-in-law “has said in the past that he wishes to draw a line under what happened and let Diana rest in peace . . . And it may be for this reason that he has not visited the memorial. It is of no consequence to me.”