Earl Spencer launched an astonishing attack on Prince Charles now king, for not visiting Princess Diana’s grave since her burial four years ago.
He implied that he believed the Prince had relegated his former wife to memory and wanted to draw a line under his marriage.
Diana, who died in a Paris car crash almost four years ago, is buried on an island on the grounds of Althorp House, her childhood home.
The Earl, Diana’s brother, said: ‘Prince Charles has an open invitation, as he knows, to come to the memorial but he has yet to take up that invitation.’
Asked by presenter Simon Mayo in a Radio Five interview why he thought that was, the Earl replied: ‘Look at it from his point of view. It’s an ex-wife at the end of the day and maybe that’s how he views it.
‘He recently said he wanted to draw a line under the whole episode and let Diana rest in peace and maybe he views him not going there as helping that process.’
When Mayo suggested Charles was being ‘extremely callous’, the Earl replied: ‘You probably think I sit at home and think about Prince Charles and his life quite a lot, but I don’t to be honest, so I think you’d have to ask him or his representatives why that might be …
‘He’s the father of my nephews and he’s very welcome to come. If he came here he’d be welcomed sincerely and with due hospitality.’
In his interview, Earl Spencer said he did not have a single friend or confidante within the Royal Family, apart from William and Harry.
And he suggested the real future of the monarchy lay with William, throwing doubt on Charles’s potential as a future monarch.
He said: ‘People obviously approve of the Queen, and we’ll see how the Prince of Wales does when it comes to his turn, but you can look down the line and see William waiting for however long it is and there is a future for the monarchy there.’
Asked if he felt he had succeeded, he replied: ‘Yes . . . I think when I wrote that I underestimated how much groundwork their mother had put in, and they were already strong enough personalities in their own right to make sure that they would find their own way in life.’
A spokesman for St James’s Palace said: ‘The matter of whether Prince Charles has visited the late Princess of Wales’s grave is a personal and private matter for him.’