The Duke of Sussex, 38, has accused The Sunday Mirror of using illegal tactics to gain stories about his life, including one article from 2003 that contained "details of private conversations I had with my father about my future, mainly that I didn't want to go to University and would rather join the Army."
As a result, the red-headed prince wasn't sure who was leaking what to the press.
"It was so conflicting. It's only now, realizing what the [Mirror Group's] journalists were doing, and how they were getting their information, that I can see how much of my life was wasted on this paranoia," Harry said. "I've always heard people refer to my mother as paranoid, but she wasn't. She was fearful of what was actually happening to her and now I know that I was the same."
Harry also touched upon how he disagreed with his brother in 2003 over whether to meet Princess Diana's former butler Paul Burrell in 2003 after he wrote a book about her.
"Both my brother and I had very strong feelings about how indiscrete Paul had proven to be with the way he had sold our mother's possessions and how he had given numerous interviews about her," Harry said. "We firmly believed that she would have expected some privacy in death, especially from someone she had trusted, and we were so upset at the way he was behaving — I didn't want to hear his reasons for it."
"Therefore, our disagreement over how to handle the situation going forward was not something I wanted splashed across the [Mirror Group's] newspapers, and I have no idea how the [Mirror Group's] journalists obtained the information within the article," he continued.
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Prince Harry claims Diana's messages were obtained by unlawful methods leading up to her August 1997 death.
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"I was devastated tonight to hear that the Daily Mirror have [sic] been telephoning my office to ask details about six meetings that are supposed to have taken place between us nobody around me knew of our Sunday evening plan," she wrote in a letter addressed to her son.
Harry wrote he "can only assume that this information had been obtained via voicemail interception and/or other unlawful information gathering such as live land linetapping."
The Mirror responded about Diana's voicemails being hacked, stating it is "total speculation without any evidential basis whatsoever."