The complaint claimed the Duchess of Sussex forced two personal assistants out of the household and was undermining the confidence of a third staff member, according to The Times.

It was made by Jason Knauf in October 2018, the couple’s communications secretary at the time.

A spokesman for Meghan and Harry said they were victims of a calculated smear campaign based on misleading and harmful misinformation.

The spokesman said Meghan was “saddened by the attack on her character, particularly as someone who has been the target of bullying herself and is deeply committed to supporting those who have experienced pain and trauma”.

The spokesman for the Sussexes said in a statement: “Let’s just call this what it is — a calculated smear campaign based on misleading and harmful misinformation. We are disappointed to see this defamatory portrayal of The Duchess of Sussex given credibility by a media outlet.

“It’s no coincidence that distorted several-year-old accusations aimed at undermining The Duchess are being briefed to the British media shortly before she and The Duke are due to speak openly and honestly about their experience of recent years.

“In a detailed legal letter of rebuttal to The Times, we have addressed these defamatory claims in full, including spurious allegations regarding the use of gifts loaned to The Duchess by The Crown.

“The Duchess is saddened by this latest attack on her character, particularly as someone who has been the target of bullying herself and is deeply committed to supporting those who have experienced pain and trauma.

“She is determined to continue her work building compassion around the world and will keep striving to set an example for doing what is right and doing what is good.”

Buckingham Palace declined to comment.

The Times has reported that a source told the newspaper the complaint was seemingly made in an effort to protect staff who Mr Knauf claimed were coming under pressure from Meghan.

The source added Prince Harry pleaded with Mr Knauf not to pursue the complaint.

It has been reported Mr Knauf sent an email to Simon Case, who at the time was Prince William’s private secretary and now the cabinet secretary, following conversations with head of HR Samantha Carruthers.

Mr Case then forwarded the email to Ms Carruthers.

In his email, Mr Knauf said she “agreed with me on all counts that the situation was very serious”.

But he added: “I remain concerned that nothing will be done.”

This is a breaking story. More to follow…