Paul Burrell thinks Princess Diana would be "heartbroken" over Prince Harry's recent public confessions and outbursts.
The former butler thinks his late boss – who tragically died in a car accident in 1997 – would "disapprove" of her son's public criticism of the British royal family in interviews with Oprah Winfrey and urge him to live a quiet, private life with his pregnant wife Meghan, Duchess of Sussex, and their 2-year-old son Archie.
Speaking to Closer magazine, Burrell said: "What he's doing now is going to make everything so much worse for him.
"Diana would be heartbroken it's come to this.
"Not only would she be devastated that Harry is cut off from his family, but she'd disapprove of him tearing down the royals.
"She'd want him to stop airing his dirty laundry and to live a quiet, private life, focused on his children."
But Burrell, 62, understands why 36-year-old Harry is still "deeply affected" by losing his mother when he was just 12 and having the eyes of the world on him as he mourned her.
He said: "There's no doubt that Harry was incredibly deeply affected by his mum's death.
"She was the closest person to him in the entire world.
"I remember him being at Kensington Palace, and breaking down, asking to have some of her personal items – like her hairbrush. It was devastating.
"But days later, he was walking the procession behind Diana's coffin with a straight face and no tears.
"He didn't want to do it at all but he was made to do that.
"I think that would have stuck with him."
The former I'm A Celebrity… Get Me Out Of Here! star thinks Harry has been "blinded" by his 39-year-old American wife but believes the former Suits actress is the only person who can intervene and stop her husband "doing any more damage".
He said: "He's been blinded by Meghan, by her beauty and by this Hollywood world.
"I think now it could only be Meghan who can stop him from doing these interviews and doing any more damage and destroying himself.
"He won't heal if he keeps doing this – it'll make things worse in the long run.
"I honestly have no idea when it will stop."