Prince Harry has lost an attempt to strike out the Mail on Sunday’s defence to his libel claim against the paper over its reporting of his dispute with the Home Office over his security arrangements.

The Duke of Sussex is suing the paper’s owner, Associated Newspapers, over a story published online and in print on 19 and 20 February 2022 relating to his legal claim against the Home Office over the downgrading of his protective security in the UK after he ceased to become a working royal.

The high court has previously ruled that the meaning of the Mail on Sunday’s story was that Harry sought “far-reaching and unjustifiably” wide confidentiality restrictions to keep his case against the Home Office secret, and that public statements made on his behalf suggested that the case was about Harry being allowed to pay for his own security when, in reality, he only made the offer to pay after the proceedings had commenced.

The judge, Mr Justice Nicklin, summarised the meaning as Harry “being responsible for attempting to mislead and confuse the public as to the true position”.

The judge found that some of the words were expressions of opinion but Harry then brought a claim to strike out the defence of honest opinion, arguing that an honest person could not have held the opinion on the basis of any fact which existed at the time the article was published.

However, the Mail on Sunday disputed the strike out claim and, in a judgment handed down on Friday, Nicklin rejected Harry’s argument, meaning that a defence of honest opinion can be deployed and the case will proceed to trial.

The judge wrote: “Overall, it is not fanciful that the defendant will be successful, at trial, in demonstrating that the public statements issued on the claimant’s behalf sought to promote the JR (judicial review) claim as his battle against the government’s (perverse) decision to refuse to allow him to pay for his own security.

“There is a real prospect that the defendant will succeed in demonstrating that this was a misleading description of the issues in the JR claim, arguably promoted because it was hoped to show the claimant’s JR claim in a positive light, whereas a portrayal of the JR claim as the claimant trying to force the government to reinstate his (tax-payer funded) state security risked his appearing in a negative light.

“I anticipate that, at trial, the defendant may well submit that this was a masterclass in the art of ‘spinning’. And, the defendant argues, it was successful in misleading and/or confusing the public. The resulting media coverage relied upon by the defendant did, indeed, characterise the JR claim as the claimant’s challenge to the government’s refusal of his offer to pay.”

Harry’s challenge to the Home Office over the downgrading of his protective security while in the UK concluded on Thursday in front of another judge, with a decision reserved until a later date. After that claim was first lodged, he later brought a separate case relating to his security arrangements, this time challenging the refusal to let him pay for police protection while in the UK. However, in May, a judge refused to allow him to bring a judicial review on that issue.

Harry’s libel action against Associated Newspapers is expected to go to trial next year.