The High Court was informed as the Duke of Sussex began his testimony that he felt “physically sick” over eight payments to private investigators connected to his late mother Diana, Princess of Wales.
Harry is suing Mirror Group Newspapers (MGN) for damages, alleging that journalists at MGN’s publications, which also include the Sunday Mirror and Sunday People, were connected to practices like phone hacking, so-called “blagging” or obtaining information by deception, and the use of private investigators for illegal purposes.
On Tuesday, the duke arrived at the Rolls Building, which was heavily guarded by police and surrounded by journalists.
He took the stand in Court 15 shortly after 10:30, swearing on a bible before the barrister for MGN began questioning him.
Harry stated in his testimony that he was “shocked and appalled” by the volume of payments made to private detectives by MGN publishers.
“I now realize that my severe paranoia of being constantly watched was not unfounded,” the duke continued.
“I was upset to discover the amount of suspicious call data and the 13 private investigator payments for Chelsy (Davy, his ex-girlfriend).
“Had she not been in a relationship with me, she would never have had to endure such a horrific experience at the hands of MGN’s journalists.
“There are even eight private investigator payments made in relation to my mother, which I have only learnt of since bringing my claim.
“This makes me feel physically sick.”
33 of the 140 articles that Harry claims were published between 1996 and 2010 and contained data obtained illegally will be taken into account during the trial.
The Duke of Sussex was being cross-examined by Andrew Green KC for MGN when he said, “Every single article has caused me distress,” to which Mr. Green replied, “Has every single article caused you distress?”
Harry replied: “Yes, without question.”
Mr Green then asked the duke about part of his case which states that he was caused particular distress “because he is a very private person” and was in the public eye at a young age.
Harry said: “I believe that as a child, every single one of these articles played an important role in my growing up.”
However, he added that he could not confirm whether he remembered reading specific articles at the time they were published, adding that there were “millions” of articles “that have been written about me since age 12”.
The Duke later said that when information he had only told to a few members of his inner circle was made public, “your circle of friends starts to shrink”.

Harry claimed that the alleged illegal activities “affected every area of my life” in his written testimony.
The Duke declared that he now thinks MGN hacked the voicemails of both himself and his acquaintances, and that it also used “other unlawful means” to collect personal data.
He continued: “The fact that the defendant’s journalists and those instructed on their behalf were listening in to private and sensitive voicemails at the level of detail discussed in this statement rather suggests that they could have heard anything and everything.
“This not only creates a huge amount of distress but presented very real security concerns for not only me but also everyone around me.
“I would say their actions affected every area of my life.”
In a trial that started last month and is expected to last six to seven weeks, the 38-year-old’s claim is being heard alongside three other “representative” claims.
MGN is disputing the charges and has either refuted or refused to acknowledge each one.
Additionally, the publisher contends that some of the claimants filed their lawsuits too late.

Just over a month after attending his father, the King’s, coronation, Harry makes a court appearance.
The Princess Royal admitted guilt to a charge under the Dangerous Dogs Act in 2002 when her pet bit two youngsters in Windsor Great Park, and it is believed that this is the first time a senior member of the royal family has directly attended in court proceedings since that time.
MGN’s attorneys stated on the opening day of the trial that the publication “unreservedly apologises” to the duke for one instance of illegal information collecting and that it accepts he is entitled to “appropriate compensation”.
According to Mr. Green, it is acknowledged that an MGN reporter at The People gave a private investigator instructions to illegally obtain information regarding Harry’s activities at the Chinawhite nightclub one night in February 2004.
“Otherwise, the specified allegations are denied, or in a few cases not admitted,” he added.
The publisher’s “unreserved apology” to the duke at the beginning of the trial for one incident of criminal action was repeated by Mr. Green in person at the commencement of the duke’s cross-examination on behalf of MGN.
He said: “MGN unreservedly apologises to you for that, it should never have happened and it will never happen again.”
Mr. Green informed Harry that “you will be entitled to, and will receive, a more extensive apology” if the judge determines that MGN was accountable for any more acts of unauthorized information acquisition.