The Duchess of Sussex’s alleged “collaboration” with the authors of a recent book about her and the Duke of Sussex is a “conspiracy theory”, the High Court has heard.

Meghan is suing Associated Newspapers (ANL) over the publication in the Mail on Sunday and MailOnline of a “private and confidential” letter sent to her estranged father Thomas Markle in August 2018.

The duchess, 39, claims the February 2019 publication of parts of the handwritten letter to Mr Markle, 76, was a misuse of her private information and breached the Data Protection Act, as well as a breach of her copyright.

At the latest preliminary hearing in London on Monday, ANL sought permission to amend its written defence to Meghan’s claim to argue she “co-operated with the authors of the recently published book ‘Finding Freedom’ to put out their version of certain events”.

The Mail’s publisher claims that the book by Omid Scobie and Carolyn Durand, which was published in August, gave “every appearance of having been written with their (Meghan and Harry’s) extensive co-operation”.

The Duke and Duchess of Sussex
The Duke and Duchess of Sussex (Daniel Leal-Olivas/PA)

Antony White QC, representing ANL, said the book “sets out in great detail accounts of events at which it is reasonable to infer that only the claimant and her husband, and/or possibly a third party who would not have spoken to the authors (eg the Queen), were present”.

He told the court that there were several instances in the book of “intensely personal information about how the claimant felt … that essentially only she knew”.

But Meghan’s lawyers argued that references in the book to her letter to Mr Markle were simply “extracts from the letter lifted from the defendant’s own articles”.

Justin Rushbrooke QC, for Meghan, said: “The claimant and her husband did not collaborate with the authors on the book, nor were they interviewed for it, nor did they provide photographs to the authors for the book.”

He added that neither Meghan nor Harry to spoke to Mr Scobie or Ms Durand, who he said “were not given the impression that the claimant wanted the contents of the letter to be reproduced in the book”.

Mr Rushbrooke told the court that ANL were simply “relying on inferences”, which he said were “riddled with factual inaccuracies”.

He referred to ANL’s reliance on a passage in ‘Finding Freedom’ which said that “Prince Harry sent a text to his father” shortly after the birth of his and Meghan’s son Archie.

The barrister added: “Well, how does that stand factually? Prince Charles, as actually is widely-known, does not have a mobile phone.”

Mr Rushbrooke said that “extracts from the letter (to Mr Markle) that the authors have reproduced are taken from the Mail’s own articles”.

He added that it was “insulting to the intelligence of us and this court” for ANL to contend that Meghan had cooperated with the authors of the book on the basis of those extracts.

Mr Rushbrooke concluded: “What the defendant is really saying, underneath the smoke and mirrors, is we don’t have any evidence for this case.”

Alexandra Marzec, also representing ANL, earlier told the court the duchess “was using her friends as, effectively, PR agents” to “influence the media” in the months before the letter was sent to Mr Markle in 2018.

ANL also argued that Meghan discussed a letter to her estranged father with the Kensington Palace communications team before she sent it because she wanted to use it “as part of a media strategy”.

The court heard that the total legal costs of both sides could be around £3 million, up to and including the trial.

The duchess is suing ANL over five articles in total, two in the Mail on Sunday and three on MailOnline, which were published in February 2019.

The headline of the first Mail on Sunday article read: “Revealed: The letter showing true tragedy of Meghan’s rift with a father she says has ‘broken her heart into a million pieces’.”

Judge Francesca Kaye said she would rule on ANL’s application to amend its defence on a later date.