The Duchess of Sussex has won her High Court privacy claim against the Mail On Sunday over the publication of a “personal and private” handwritten 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 the letter sent to 76-year-old Thomas Markle in August 2018.

She is seeking damages for alleged misuse of private information, copyright infringement and breach of the Data Protection Act over five articles published in February 2019, which included extracts from the “private and confidential” letter to her father.

Her lawyers argued, at a hearing in January, that ANL has “no prospect” of defending her claim for misuse of private information and breach of copyright.

They asked the High Court to grant “summary judgment” in relation to those claims, a legal step which would see those parts of the case resolved without a trial.

In a judgment on Thursday, Mr Justice Warby ruled that the publication of Meghan’s letter to her father was “manifestly excessive and hence unlawful”.

The judge 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.”

He ruled: “The claimant had a reasonable expectation that the contents of the letter would remain private. The Mail articles interfered with that reasonable expectation.”

The judge added: “There is no prospect that a different judgment would be reached after a trial.”

In relation to Meghan’s copyright claim, Mr Justice Warby found that the publication of the letter – which he described as “a long-form telling-off” – did infringe her copyright.

But the judge said the issue of whether Meghan was “the sole author” of the letter or Jason Knauf, formerly communications secretary to the Duke and Duchess of Sussex, was a “co-author” should be determined at a trial.

Mr Justice Warby said that there would be a further hearing in March to decide “the next steps” in the legal action.

Meghan’s data protection claim was not considered at the hearing in January and is still outstanding.

The duchess sued ANL in September 2019 over five articles in the Mail On Sunday and MailOnline, which were billed as a “world exclusive” featuring “Meghan’s shattering letter to her father”.

A double-page spread in the Mail On Sunday carried the headline: “Revealed: the letter showing true tragedy of Meghan’s rift with a father she says has ‘broken her heart into a million pieces’”.