A bid by the Duke of Sussex to rely on a “secret agreement” between Buckingham Palace and a tabloid publisher in his claim over alleged unlawful information gathering will be decided by Britain’s High Court.

Prince Harry, 38, alleges he was targeted by journalists and private investigators working for The Sun and the now-defunct News Of The World, and is suing the publisher, News Group Newspapers.

The duke alleges he was targeted by journalists and private investigators working for the papers.

At a preliminary hearing in April, the publisher asked a judge to throw out Harry and Hollywood star Hugh Grant’s claims, arguing they were brought too late.

Justice Fancourt ruled earlier that Grant’s claim could go to trial, except for any allegations relating to phone hacking.

Harry’s lawyers have argued NGN’s challenge to his claim is an attempt to go behind the alleged “secret agreement” between the royal family as an institution and the publisher, which the duke was informed of in 2012.

NGN, which denies any unlawful activity at The Sun, disputes that any such agreement exists.

Justice Fancourt will hold a hearing in London on Wednesday to decide whether Harry’s pleaded case can be amended to include his secret agreement claims.

Grant, 62, is bringing a similar legal action against NGN in relation to The Sun only, having previously settled a claim with the publisher in 2012 relating to the News Of The World.

In May, the judge ruled that Grant’s claims over alleged unlawful information gathering – other than his allegations of phone hacking – can go ahead to a trial in January.

During a three-day hearing in April, lawyers for NGN argued Harry and Grant had been “front and centre” of allegations against the publisher over hacking and therefore could not have failed to realise they had a potential damages claim much sooner.

The Duke of Sussex’s lawyers argued he was aware of unlawful activity about 2012, he but had no reason to think it had taken place at The Sun, and was prevented from bringing a claim because of a “secret agreement” between the royal family and senior NGN executives.

His barrister David Sherborne said in written arguments the late Queen was involved in “discussions and authorisation” of the agreement, which was that members of the royal family would not pursue claims against NGN until after the conclusion of litigation over hacking.

Mr Sherborne said the agreement “meant that the claimant could not bring a claim against NGN for phone hacking at that time”.

Anthony Hudson KC, for NGN, said the publisher’s position was “there was no such secret agreement”.

Justice Fancourt is expected to give his ruling on whether the duke’s claims can go ahead to trial after deciding on the “secret agreement” issue.

In April, Mr Sherborne told the court correspondence in 2017 and 2018 between the late Queen’s then-director of communications Sally Osman, Robert Thomson and Rebekah Brooks was “consistent” with there being such an agreement.

Ms Brooks is the chief executive of News UK and Mr Thomson is chief executive of News Corp, both parent companies of NGN, owned by Rupert Murdoch.

NGN has previously settled several claims since the phone-hacking scandal broke in relation to the News Of The World, which closed in 2011. It has consistently denied any unlawful information gathering took place at The Sun.

– AAP