Prince Charles slammed ex-royal butler Paul Burrell as “pathetic” in an unearthed letter going up for auction.
The handwritten note, over four pages, rails against Royal household staff who 'exercise their pathetic jealousies and vendettas in public'.
Charles penned the note in 2002, weeks after Burrell - Diana’s ex-butler - had gone on trial on theft charges relating to 310 of items worth £4.5m belonging to the late princess.
The Old Bailey trial collapsed part-way through after the Queen recalled that Burrell had told her he was keeping some of Diana's possessions.
In the letter to Marjorie Dawson, who was the personal maid and dresser to Princess Alexandra for 36 years- Charles lamented the “ghastliness” of the episode.
The Prince of Wales wrote in November 2002: “Bless you for taking the trouble to write as you did in the wake of all the ghastliness that has been going on!
"I find it utterly incredible, as I have done nothing but show people like Paul Burrell every consideration over the years.
"Unfortunately we are now to be treated as mere pawns in a terrifying and ongoing media circulation war where the actual facts are totally disregarded and vast sums of money are offered as bribes to former and current members of staff to exercise their pathetic jealousies and vendettas in public.
"One member of staff has been offered a total of £5 million by the newspapers in recent weeks."
The four page letter is being sold by a collector and is tipped to sell for £2,000 by London-based Chiswick Auctions on July 21.
Valentina Borghi, specialist at Chiswick Auctions, said: "It is rare to find a letter from Prince Charles which is so open about his feelings.
"It was a difficult time for the Royals and I believe he was pretty upset when he wrote this letter.
"We are used to a much calmer version of Prince Charles, so he must have been very hurt when so many people he thought he could trust were willing to make money by selling private facts about his family."
Diana died in a car crash in Paris in 1997, while Burrell released a memoir, A Royal Duty, in 2003.
It led to a rift with Buckingham Palace, with Prince William and Prince Harry calling the book a 'cold and overt betrayal' of their late mother.
Earlier this month it was revealed Paul Burrell , Diana’s trusted butler, was willed £50,000.
William and Harry were the main beneficiaries after being left without their mother, who would have turned 61 on Friday July 1 if she was still alive.
A discretionary fund outlined benefits for the princes, their future spouses and family members, and special charities received £100,000, plus Princess Diana’s wardrobe, including her famed wedding dress .
