Earl Spencer last night hit back in his bitter war of words with King Charles and declared: ‘I’m telling the truth.’

In an escalation of the feud sending shockwaves through the Royal Family, Princess Diana‘s brother claimed he told friends and family ‘straight away’ about an alleged outburst by the then-Prince of Wales ‘because it was so monstrous’.

The Daily Mail, which is exclusively serialising the earl’s bombshell memoir, this week revealed the incendiary claim that – days after Diana’s 1997 death – Charles told him: ‘Rest assured, we’ll forget her soon enough.’

It prompted an extraordinary Palace statement, with royal aides questioning the veracity of the earl’s account and suggesting that grief can ‘cloud reason, affect judgment and colour memory’.

But last night, in an interview with the BBC, the 62-year-old earl said: ‘I can tell you here and now, those are exactly the words he said.’

He added: ‘I’ve only ever had two calls on the line with Prince Charles at any stage of my life.

‘I was hyper alert to what he was saying and those are precisely the words he said and I promise that to you now. Genuinely, that is what he said. I don’t hear him saying he didn’t say that.’

Told by Laura Kuenssberg how the Palace’s unprecedented statement showed the King was ‘plainly furious’, Earl Spencer replied: ‘Is he furious or is he embarrassed?’

In the latest compelling extract of the memoir that has sparked the row between the former brothers-in-law, published in today’s Mail, the earl lambasts the Royal Family for a ‘lack of obvious care’ for Prince Harry in the wake of Princess Diana’s funeral.

In the memoir – entitled Swan Song: Diana, My Sister – the earl writes that Harry, who was 12 at the time of his mother’s death, ‘needed Diana’s hugs’ but was instead ‘allowed to spin out of control’.

He says ‘a more caring hand’ at such moments would have helped Harry ‘enormously in the future’ but instead the young prince ‘seemed so very alone in his despair and torment’.

He also reveals that he read his eulogy to Diana’s coffin in Chapel Royal, a private chapel at St James’s Palace where his sister’s body lay for five days before her funeral.

Read More: ‘I’m telling the truth. His words were monstrous’: Earl Spencer hits back at Charles in defiant interview about his call with the King in the days after Diana’s death