The Duke of Edinburgh wrote "cruel and disparaging" letters to Princess Diana, an alternative therapist has told the inquest into her death.
Princess Diana's death has been the source of conspiracy theories
Simone Simmons, who practises "energy healing", told the London hearing the princess had shown her two letters from Prince Philip dating from 1994 or 1995.
Ms Simmons said the duke had made observations about the propriety of the princess's behaviour.
Diana and her companion Dodi Al Fayed died in Paris in a car crash in 1997.
The BBC's Nicholas Witchell says Ms Simmons first met Diana in 1993 and had an ongoing friendship with the princess, although the pair did fall out several times.
Ms Simmons told the inquest that one of the letters from Prince Philip she had seen was handwritten, and the other was typewritten.
"Diana read one out to me," she said. "She was absolutely furious, she was imitating the duke's voice at the time and at the end she said: 'What a cheek.'"
Ms Simmons also said Diana had given her a copy of a dossier about the landmine industry she had compiled during her campaign against the weapons.
The therapist said she had hidden this under her mattress, along with other documents from the princess.
Ms Simmons said the landmines dossier was several inches thick but that she had burnt it after Diana's death because she was afraid of what might happen to her.
She said: "I believed that if they could bump Diana off, then they could bump anyone off - and I value my life."
However, just before she left the witness box, Ms Simmons agreed with counsel for the inquest that no member of the Royal Family "would ever have harmed" the princess.
The jury at the inquest has previously seen extracts of other letters between Princess Diana and Prince Philip.
That correspondence, presented to the High Court hearing by Prince Philip's private secretary, Brigadier Sir Miles Hunt-Davis, dates from between June and September 1992.
In those handwritten replies, the princess referred to him as "Dearest Pa" and praised his "great understanding and tact".
The inquest continues.