The Buckingham Palace investigation into bullying will be confined solely to allegations concerning the Duchess of Sussex and will not involve any other members of the Royal family.
The review will be deliberately limited in scope, focusing on a specific time period, and will invite only members of staff from the time to give evidence, The Telegraph understands.
A senior royal aide denied claims that the Duchess of Cornwall or the Duchess of Cambridge would be involved, insisting that it was solely for employees.
A Sunday newspaper claimed that the senior royals could be called upon to assist palace officials in the probe if participants claimed they had witnessed the offending behaviour.
The Duchess of Cambridge, in particular, is said to have been unhappy with the way her sister-in-law spoke to her staff. She was once said to have been left in tears after a confrontation during Princess Charlotte’s bridesmaid dress fitting.
But a well-placed source said: "Only staff will take part in this review, no one else."
The investigation is expected to be led by Elisabeth Hunka, director of HR at Buckingham Palace. She could be aided by Catherine James, the treasurer of Prince Charles's household, who is responsible for HR at Clarence House.
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Members of staff past and present will be invited to give evidence in confidence.
It has been claimed that up to a dozen aides have already lined up to take part.
The Sussexes have made clear that if allegations are made against them, they expect to be formally notified and given the right of reply.
However, the palace has stressed that the review is designed solely to improve internal policies and procedures and will not be treated as a “kangaroo court”.
It was set up after it emerged that an official complaint had been raised about the Duchess’s behaviour by Jason Knauf, then the Sussexes’ communications secretary.
In an email complaint sent in October 2018 to Simon Case, who was then the Duke of Cambridge's private secretary and is now the cabinet secretary, he said: “I am very concerned that the Duchess was able to bully two PAs out of the household in the past year. The treatment of X was totally unacceptable.”
He added: “The Duchess seems intent on always having someone in her sights. She is bullying Y and seeking to undermine her confidence. We have had report after report from people who have witnessed unacceptable behaviour towards Y.”
The Duchess denies bullying. A source close to them said: "This is a tit-for-tat scenario. If this was a private company, we've already quit, or been fired, depending on your point of view."
A spokesman for the couple said they were victims of a "smear campaign based on misleading, harmful misinformation". Their lawyers said the allegations were part of a "wholly false narrative" peddled by the Palace.
Palace aides also strongly denied yesterday that there were any plans to strip the Sussexes of their royal titles, a controversial move that would effectively rip up the “Sandringham Agreement” made about the couple’s departure from royal life last year.
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