Earl Spencer has hinted that his nephews, Prince William and Harry, already knew his shocking revelations about King Charles.

He claimed that days after Diana’s 1997 death, the then Prince Charles had gone ‘ballistic’ in a phone call and told him: ‘Rest assured, we’ll forget her soon enough’.

It was thought that William and Harry had not been aware about the explosive contents of Earl Spencer’s forthcoming memoir to his sister.

But in an interview with the BBC’s Laura Kuenssberg, he said: ‘I don’t like to talk about what I’ve been speaking about to William and Harry, but this will not be a surprise to them.’

He clarified: ‘I will tell you that these words will not be a surprise to them.’

Earl Spencer said that then Prince Charles went ‘ballistic’ after he told him that Diana wouldn’t want her young sons making the public walk behind her coffin.

He told Laura Kuenssberg: [Prince Charles] said, “I gather you don’t think William and Harry should walk behind Diana’s coffin.

‘And I said, “Of course not, sir. She wouldn’t want it. And then he said, “Well, I walked behind Lord Mountbatten’s coffin, and I said, “Yes, but you were 30, and he wasn’t your mother.”

‘And then to me, he went ballistic would be the right term, and started really going for my family as a whole about their sense of duty not being adequate enough, and ranted for a while.

‘I have no idea how long, but it was a significant period, and I just listened. And then he stopped, and I thought, oh, now, now he’s going to pull himself together and say something more appropriate, and then he said, “We’ll forget her soon enough.”

He added Charles even allegedly sounded ‘giddy’ on the phone with him.

‘I’d had a lot of calls that day from people who cared, who were stunned… and I just felt there was a lightness in his tone about Diana’s death that really jarred with me.’

Earl Spencer has given his rebuttal to Buckingham Palace’s blistering statement that ‘the pain of fraternal grief can cloud reason, affect judgment and colour memory’ insisting ‘I’m telling the truth’.

Kuenssberg asked him: ‘So the king is giving an impression to the country that’s not true, misleading people, even lying?’

Spencer replied: ‘All I can tell you is what was said and what I heard and what shocked me. What else would have made me hang up on the king that day, it was something as outrageous as that slur against Diana.’

In the emotional interview, Earl Spencer spoke about growing up with Diana and insisted that he would never pick sides between Prince William and his brother Harry.

‘I’m on my deceased sister’s sons’ side, both of them. And if either of them wanted anything then I’d be equally there for them,’ he said.

‘And I never get involved in one camp or the other, except as a benign figure I hope.’

He hinted at a ‘lot of reasons on both sides’ why the rift between the siblings had ‘got to this stage’.

‘I hope one day it’s resolved, but I don’t know all – I certainly don’t know what’s been done in the finer detail and so I would feel intrusive if I got more involved than to say of course a mother would want her two sons to be happy together and love each other’.

He even recounted the night he got the call from his sister Lady Jane Fellowes, who said Princess Diana had been in a crash but ‘it’s not too serious’.

But as he looked for updates he got more distressing news from his sister.

‘And then my sister Jane said, “I’m afraid she’s died.” It started… as a little prang, and then it became a broken leg, perhaps a head injury, and then death.’

He explained Diana rang up her brother to tell him the reason she was getting divorced, telling him: ‘My husband is in love with his valet’.

‘I told her, “I do worry that the public will really be, in a way, angry with you for killing the fairy tale that they’ve all subscribed to”, and those are the words she said to me.’

Spencer even hinted there could be more Royal family secrets which have been ‘left unsaid.’

BBC’s Laura Kuenssberg asked him: ‘Maybe some family secrets are better left unsaid.’

He replied: ‘They certainly are, and they have been left unsaid.’

But will it be Earl Spencer who will spill the beans? He claims: ‘Nope, that’s it.

‘That’s me done.’

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