This is the first appearance of a member of the royal family at the helm in more than a century. Prince Harry arrived at the High Court in London on Tuesday morning to testify against a tabloid accused of hacking phone messages.
The 38-year-old Duke of Sussex arrived at the court in a black car and then entered the court without saying a word to the dozens of journalists waiting for him.
Exiled in California with his wife Meghan, the youngest son of King Charles III, in delicate with the rest of the British royal family, has initiated a series of legal proceedings against British newspapers.
Read alsoMirror, Sun, Daily Mail... Prince Harry's crusade against tabloid newspapers begins
His presence at the High Court in London for the lawsuit against the publisher of the Daily Mirror gives considerable media weight to his fight against the tabloid press. He considers the latter responsible for the death of his mother Diana, chased by paparazzi in Paris in 1997 and also accuses her of harassment towards Meghan.
The prince had been summoned as early as Monday, but he did not show up on the grounds that the second birthday of his daughter Lilibet on Sunday had not allowed him to fly in time from Los Angeles. Judge Timothy Fancourt did not hide his annoyance Monday, saying he was "a little surprised", which suggests tense exchanges with Harry.
In the ongoing trial, which began last month, Harry accuses the publisher of the Daily Mirror of using illicit processes to gather information, including hacking into telephone messages, between 1996 and 2010.
This is the first appearance of a member of the royal family at the bar since that of the future Edward VII in 1891 for a defamation lawsuit.
Thirty-three disputed articles were retained by the judge in the proceedings out of 147 targeted by Harry. Setting out the prince's grievances, his lawyer said the media group had used the services of "at least 30 private detectives".
Harry has been the victim of illegal information collection "from childhood at school" to adulthood, his lawyer David Sherborne said Monday, adding that "nothing is sacrosanct or out of bounds".
"No aspect of the young prince's life was protected" from press intrusions, the lawyer said, citing his romantic relationship and an argument with his brother William.
At the beginning of the trial, the Mirror Group Newspapers (MGN) - which in addition to the Daily Mirror newspaper publishes Sunday Mirror and Sunday People - issued an "unreserved" apology, acknowledging "some evidence" of illegal information gathering. The publisher's lawyer, Andrew Green, on the other hand, rejected the accusations of interception of voice messages and highlighted the age of the facts. "There is simply no evidence to conclude that the Duke of Sussex was hacked," he said.
Paparazzi in New York
Prince Harry's last appearance in the UK was on his whirlwind trip to his father's coronation on May 6. He has kept a distance from his father and brother, crown heir William, whom he slammed in his memoirs published in January.
Charles III is this time on a private visit to Romania and therefore a reconciliation seems unlikely again.
At the end of March, Harry had created the surprise by appearing at the High Court - but in the public - on the occasion of a preliminary hearing against ANL, the publisher of the Daily Mail, accused of the same methods by a series of personalities including the singer Elton John.
Two weeks ago, Prince Harry lost the lawsuit he had filed for police protection when he travels to the UK.
In a sign of the intensity of tension between Harry and the press, Harry and Meghan's spokesman claimed last month that the couple had been "chased" in New York by "very aggressive paparazzi". An episode that revived the memory of Diana's death.