Emails disclosed to the High Court last year revealed that in 2018, the late Queen approved a decision to threaten News Group Newspapers (NGN) with legal action, apparently frustrated with the publisher’s lack of response to hacking claims.

But Harry has also alleged in court documents that his grandmother knew about a so-called “secret agreement” between Buckingham Palace and the publisher of The Sun under which the royals agreed not to sue.

The allegation was strongly denied by all sides and rejected as “implausible” by a judge.

David Sherborne, Harry’s barrister, told the High Court earlier this year that he might have to settle before the case gets to trial due to the “impossible” legal costs.

However, Harry told ITV that he was determined to see it through to the end, insisting that he was the only person who could do so.

“I don’t think there’s anybody else in the world that is better suited to be able to see this than myself,” he said. “I’m trying to get justice for everybody.”

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He added: “If I can get to trial, we’re talking over a decade’s worth of evidence that has never been heard. That’s the goal.

“That evidence needs to come to the surface and after that, the police can make their mind up because the public and this country deserve better.”

However, the Duke admitted that it was a “risk” and that it had been a “hard decision” due to the negative attention it had generated.