King Charles too busy to see Prince Harry during surprise return to London for court case

King Charles is too busy to see his son Prince Harry who has returned to London for a High Court appearance.

That's despite the monarch having a last-minute, two-day gap in his diary following the postponement of his France visit.

So too are the Prince and Princess of Wales, who are out of the capital for the school holidays.

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The Duke of Sussex made a surprise return to the UK to attend a four-day preliminary hearing on Monday.

He is one of several high-profile figures taking legal action against Associated Newspapers Limited, the publisher of the Daily Mail, over alleged phone hacking and misuse of private information.

Prince Harry arrived at court shortly after 10.30am and later sat inside alongside his lawyers.

He flew in from Montecito, in California, to show his "support" for the case, The Telegraph UK reports.

The case has been brought by a group of celebrities including Sir Elton John and his husband David Furnish, Elizabeth Hurley and Sadie Frost. Sir Elton, Furnish and Frost were also in court.

The accusation relates to the placing of listening devices in private homes and cars, and other breaches of privacy.

The group alleges phone-tapping, paying police officials for sensitive information, and impersonating individuals to obtain medical records.

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Associated Newspapers has denied the claims.

Prince Harry is understood to have made contact with his father about returning to London, but was told the King is too busy to see him while he is there, the publication reports.

The King is understood to be at Highgrove, in Gloucestershire, after being forced to postpone his visit to France due to ongoing protests over Emmanuel Macron's pension reforms.

He and the Queen Consort will visit Germany on Wednesday, as planned.

Prince Harry's decision to attend the hearing in London may have overshadowed the King's first state visit as monarch, had it gone ahead.

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The duke is also unlikely to see his brother and sister-in-law who are staying at their country home Anmer Hall in Norfolk.

Because of school holidays, Prince William and Catherine and their three children, are not in London or Windsor.

Harry's return to the UK also comes as a surprise due to his ongoing concerns regarding security.

His wife, Meghan, and their two children Prince Archie and Princess Lilibet, have not joined him.

Harry's previously said it's unsafe for him and his family to be in the UK after their tax-payer funded police protection was removed when they stepped back as senior working royals.

This time, Prince Harry was flanked by private security guards – a method he employed when he and Meghan returned to the UK in September last year, days before his grandmother the Queen died.

In a separate case, Prince Harry is one of several high-profile figures suing the Mirror Group Newspapers over allegations of phone hacking.

Harry's expected to give evidence at that High Court trial, which begins on May 9, the day after King Charles' coronation weekend.