Lord Stevens has described the moment he quizzed Prince Charles about the death of Princess Diana.

The former commissioner of the Metropolitan Police had to interview the future king after her butler Paul Burrell wrote a letter saying Diana thought she ‘might be murdered’ before her untimely death.

Prince Charles was interviewed by Lord Stevens and former Met Detective Chief Superintendent David Douglas but denied he had any involvement in his wife’s death in a Paris tunnel on August 31, 1997.

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Lord Stevens describes interview with Charles about Diana’s death

Lord Stevens has described the moment he quizzed Prince Charles about death of Princess Diana

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This year marks the 25th anniversary of Princess Diana’s death in Paris on August 31, 1997. Channel 4’s documentary Investigating Diana: Death in Paris has investigated circumstances around her death. (Pictured: The Princess of Wales in a red and black Catherine Walker evening dress during an official visit to Paris in November, 1988)

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Former commissioner of the Metropolitan Police Lord Stevens had to interview the future king after her butler Paul Burrell wrote a letter saying Diana thought she ‘might be murdered’ before her untimely death.

Lord Stevens said: ‘I wasn’t frightened of the establishment. The decision was made to see Prince Charles because of the Burrell letter and the allegations made in that letter.

‘Princess Diana had stated that she was going to be murdered by her husband. We had to see whether there was any substance to that and we had to have his reply to it.

‘I’m sure something like that had not ever happened before so that was unprecedented.’

He added: ‘[Prince Charles] understood the reason for it and was only too willing to cooperate. He was extremely charming.

‘He denied being involved in an way and that was noted.’

Meanwhile, David Douglas said: ‘I’m not obsessed with the royal family in any way, shape or form. Charles was very polite.

‘Lord Stevens asked him questions and he deliberately leaned past Lord Stevens to ask me general questions – “Is the inquiry going okay?”‘

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David Douglas was the senior investigating officer on Operation Paget and said he thought Prince Charles was ‘classy’

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He said: ‘I’m not obsessed with the royal family in any way, shape or form. Charles was very polite’

Mohammed Al-Fayed gave VIAGRA and BULL’S TESTICLES to Lord Stevens

‘He was putting me at ease by including me in the conversation. I thought that’s quite classy. I was impressed with that.’

He added: ‘When it came to the details, he couldn’t understand any of it.

‘He couldn’t understand why it was written, why those names were put in there.

‘He just couldn’t understand any of it.’

Channel 4’s documentary Investigating Diana: Death in Paris comes in the year marking the 25th anniversary of Princess Diana’s death in Paris on August 31, 1997.

Prince William and Prince Harry were ‘kept in the dark’ over the documentary, sources have claimed.

A co-production between Channel 4 and Discovery Plus, it claims to explore ‘how powerful individuals, the press and the internet created and fuelled conspiracy theories that overwhelmed facts and called into question the very nature of truth’.