Prince Harrymade a surprise appearance in London on Monday.

The Duke of Sussex, 38, attended the High Court for the first day of a legal case in which he and other prominent figures includingElton John,Elizabeth HurleyandJude Law’s ex-wife Sadie Frost are suing Associated Newspapers Ltd (ANL), publisher of theDaily MailandMail on Sunday, for illegal information gathering.

The four-day hearing will consider legal arguments from both sides and will conclude with a judge’s ruling on whether the case should go to trial. Associated Newspapers are arguing that the case should be thrown out.

It is the first time Prince Harry has been in the U.K. since the funeral of his grandmotherQueen Elizabethin September. PEOPLE understands that he jetted into London to show his support for the case and informed both his fatherKing Charles, 74, and brotherPrince William, 40, that he would be in the U.K. and attending the proceedings.

Prince Harry arrives at the High Court in London.Justin Ng / Avalon

Prince Harry arrives at The Royal Courts Of Justice in London

Harry willlikely not see Williamwhile he is in the U.K., however, as the Prince of Wales is currently taking some time off with his wifeKate Middleton, 41, as their three children —Prince George, 9,Princess Charlotte, 7, andPrince Louis, 4 — are on a school break.

Prince Harry.Jordan Pettitt/PA Images via Getty Images

The Duke of Sussex arrives at the Royal Courts Of Justice, central London

It isnot expected that he will seehis father,King Charles, 74, either. The British monarch wasdue to be in Franceat the beginning of his now-postponed tour. The King and Queen Camilla, 75, will leave for Germany on Wednesday instead.

Elton John.James Veysey/Shutterstock

Elton John arrives in his role as claimant at the Royal Courts of Justice

Associated Newspapers deny the allegations, calling them “preposterous smears,” the BBC reported.

Prince Harry on March 27.Justin Ng / Avalon

Prince Harry arrives at The Royal Courts Of Justice in London

The other claimants in the case are John’s husbandDavid Furnish, Baroness Doreen Lawrence, who is the mother of race-attack victim Stephen Lawrence and Sir Simon Hughes, a leading Liberal Party politician and former U.K. government minister.

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Justin Ng / Avalon

Prince Harry arrives at The Royal Courts Of Justice in London

The lawsuit is just one of a number of cases that the Duke of Sussex is involved in against British newspaper groups.Prince Harryis also undertaking aseparate libel lawsuitagainst Associated Newspapers centering on aMail on Sundayarticle about the royal’s legal battle with the British government over his police protection in the country.

source: people.com