The files showed that Ferguson took her daughters, then aged 19 and 20, to visit Jeffrey Epstein in New York just five days after he was released from prison for child sex crimes.
Epstein was then under house arrest after serving 12 months in a Florida jail for soliciting a minor for prostitution.
The emails also showed Mountbatten-Windsor sent photos of his daughters to Epstein in 2010 and 2011.
In a March 2010 email, Ferguson told Epstein that she was “waiting for Eugenie to come back from a shagging weekend”.
The files have prompted claims that the princesses have been frozen out by the royal family. It has been suggested that the King will not invite them to Ascot this summer, an event at which they have long been a regular fixture.
However, the princesses have distanced themselves from their parents and the wider royal family since the files were published.
They have not been seen with their parents since Mountbatten-Windsor’s arrest and are not expected to attend high-profile events with the royal family for the foreseeable future.
There is no suggestion of wrongdoing on their part, and they are said to have been left distraught by the allegations about their father.
The King has previously signalled his support for his nieces and allowed them to walk with the royal family at Sandringham even after he stripped his brother of his titles and honours.
Mountbatten-Windsor was arrested on suspicion of misconduct in public office in February over accusations he shared confidential information with Epstein while serving as Britain’s trade envoy.
Thames Valley Police is assessing claims in the Epstein files that suggest the former prince sent the paedophile financier sensitive government emails from 2001 to 2011.
It has also been reported that police may widen their investigation to assess potential corruption offences. Mountbatten-Windsor has always denied wrongdoing.
The former duke moved out of Royal Lodge earlier this year after three million documents related to Epstein, published by the US Department of Justice, further exposed his links to the paedophile.
Mountbatten-Windsor features a number of times in the documents, including images apparently showing him crouched over an unidentified woman in what appears to be Epstein’s New York mansion.
The files also revealed that Ferguson had called Epstein her “supreme friend”, had apologised for her public criticism of him and had begged him for money.
Last week, she was stripped of her honorary Freedom of the City of York, while several charities cut ties with her and six companies linked to her started winding down.
Earlier this month, Eugenie resigned as patron of Anti-Slavery International, a charity with which she had been involved since 2019.
The princesses have not publicly responded to the Epstein Files or previous allegations against their parents.
Meanwhile, the King and Queen will be joined by other members of the family as they attend the traditional Easter Matins service at St George’s Chapel, Windsor, which will be followed by a private lunch at Windsor Castle.
The Prince and Princess of Wales and their children are expected to attend. Last year, they spent the bank holiday in Norfolk with Prince George, Princess Charlotte and Prince Louis.
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