The Duke of Sussex has said his decision to fight against intrusion from the tabloid press has been a “central piece” behind the breakdown of his relationship with the rest of the Royal Family.

In December a High Court judge ruled that Mirror Group Newspapers (MGN) had unlawfully gathered information for stories published about Prince Harry – and he has since been awarded hundreds of thousands of pounds in damages.

Speaking for the first time since the four-year legal battle concluded, he said he felt “vindicated” by the ruling, calling it a “monumental victory”.

But in comments due to be aired as part of an ITV documentary on Thursday, Prince Harry added “it would be nice if we did it as a family”.

Prince Harry, who became the first British royal in 130 years to give evidence in a court, told the programme his decision to fight these cases had “caused… part of a rift” with the rest of his family.

He and his wife, Meghan, stepped back as senior royals in 2020 after publicly revealing their struggles under the media spotlight.

The prince, who now lives in the US state of California, also said he believed there was evidence his mother – the late Princess Diana – was hacked, claiming she “was probably one of the first” victims.

This has never been proven in court.

“The press, the tabloid press very much enjoy painting her as being paranoid, but she wasn’t paranoid, she was absolutely right of what was happening to her,” he said.

Referring to one headline from the Daily Mirror brought up in his case against MGN which claimed his then-girlfriend Chelsy Davy was preparing to break up with him, the prince said it “seems as though they knew something before I even did”.

“I think there’s a lot of… paranoia, fear, worry, concern, distrust in the people around you, clearly a headline like that has absolutely no public interest whatsoever,” he said.

The interview is due to air in a new ITV documentary, Tabloids on Trial, on Thursday evening.

The programme speaks to other famous faces – including Hugh Grant, Charlotte Church and Paul Gascoigne – whose lives have been impacted by the press.

In response to the documentary, an MGN spokesperson said: “We welcomed the judgment in December 2023 that gave the business the necessary clarity to move forward from events that took place many years ago.

“Where historical wrongdoing took place, we apologise unreservedly, have taken full responsibility and paid compensation,” the spokesperson added.

The case was just one of a series of legal challenges the prince has brought against parts of the British press.

Cases against Associated Newspapers – the publisher of the Daily Mail – and News Group Newspapers – now News UK, which publishes the Sun – are currently making their way through the courts.