The High Court is set to hear the latest round in the legal battle between the Duchess of Sussex and The Mail On Sunday over the publication of a “personal and private” letter to her estranged father.

Meghan, 39, sued Associated Newspapers Limited (ANL), the publisher of The Mail On Sunday and MailOnline, over a series of articles which reproduced parts of a handwritten letter sent to Thomas Markle, 76, in August 2018.

She claimed the five articles, published in print and online in February 2019, misused her private information, infringed her copyright and breached the Data Protection Act.

In February, the High Court granted Meghan summary judgment in relation to her privacy claim, meaning she won that part of the case without having to go to trial, as well as most of her copyright claim.

At a remote hearing on Wednesday, Lord Justice Warby will deal with what “financial remedy” or damages the duchess can pursue at a further hearing, which is expected to take place in October.

Duchess of Sussex High Court case
The Duke and Duchess of Sussex arriving at the Royal Albert Hall in London to attend the Mountbatten Festival of Music (Simon Dawson/PA)

The court will also consider how the remaining parts of Meghan’s copyright claim should proceed, as well as what should happen with her data protection claim against ANL.

In March, the publisher was ordered to print a statement on the front page of The Mail On Sunday and a notice on page three of the paper stating it “infringed her copyright” by publishing parts of the letter to Mr Markle.

Lord Justice Warby later ruled that the statement did not have to be published “in the same position, and be in the same size font, as the front-page trailer complained of”.

But the front-page statement about Meghan’s victory in her copyright claim was put on hold, to allow ANL time to seek permission to appeal.

In the summary judgment ruling in February, Lord Justice Warby said ANL’s publication of Meghan’s letter to her father was “manifestly excessive and hence unlawful”.

Duchess of Sussex High Court case
The Daily Mail Masthead (Jonathan Brady/PA)

He said: “It was, in short, a personal and private letter.

“The majority of what was published was about the claimant’s own behaviour, her feelings of anguish about her father’s behaviour, as she saw it, and the resulting rift between them.

“These are inherently private and personal matters.”

The judge said “the only tenable justification for any such interference was to correct some inaccuracies about the letter”, contained in an article in People magazine, published just days before ANL’s five articles, which featured an interview with five friends of Meghan.

But Lord Justice Warby added: “The inescapable conclusion is that, save to the very limited extent I have identified, the disclosures made were not a necessary or proportionate means of serving that purpose.

“For the most part they did not serve that purpose at all.

“Taken as a whole the disclosures were manifestly excessive and hence unlawful.”

He also said ANL’s arguments on ownership of the copyright of the letter “seem to me to occupy the shadowland between improbability and unreality”.

The remote hearing before Lord Justice Warby begins at 10.30am and is expected to last for two hours.