Prince Charles Told Princess Diana He Didn't Love Her the Night Before Their Wedding, Her Friend Claims

The night before their fairytale wedding, Prince Charles dealt Princess Diana a "devastating" blow.

Penny Thornton, an astrologer consulted by Diana, spoke out about the bombshell claim in ITV's new documentary The Diana Interview: Revenge of a Princess, airing Thursday in the U.K. 25 years after her famous interview on BBC's Panorama.

"One of the most shocking things that Diana told me was that the night before the wedding Charles told her that he didn't love her," Thornton said. "I think Charles didn't want to go into the wedding on a false premise. He wanted to square it with her and it was devastating for Diana."

Thorton added, "She didn't want to go through with the wedding at that point; she thought about not attending the wedding."

RELATED: Princess Diana's Friend Says Panorama Interview Contributed to Her Death

Terry Fincher/Princess Diana Archive/Getty Images Princess Diana and Prince Charles on their wedding day

Bettmann/Getty Princess Diana and Prince Charles

During her 1995 BBC interview with reporter Martin Bashir, Princess Diana revealed that both she and Prince Charles were involved in affairs during their marriage. Prince Charles resumed a relationship with ex-girlfriend (and current wife) Camilla Parker-Bowles, contributing to their 1992 separation.

When Bashir asked Princess Diana if Camilla was a "factor" in the marriage's breakdown, Diana replied: "Well, there were three of us in this marriage, so it was a bit crowded." The stunningly candid quote soon echoed around the world.

Diana also confirmed her relationship with British former cavalry officer James Hewitt. When Bashir asked her if she was unfaithful to Charles, she said about Hewitt, "Yes, I adored him. Yes, I was in love with him."

PA Images Princess Diana during her Panorama interview

The new ITV documentary alleges Bashir doctored bank statements to coerce Princess Diana into speaking out. Earlier this month, Diana's brother Charles Spencer, the 9th Earl Spencer, publicly accused the BBC of sending him a "piecemeal apology" for the use of fake documents that were utilized to help secure the famous interview with his sister.

A 1996 BBC internal investigation claimed that the faked papers had "no bearing" on the interview. However, Spencer dismissed these findings and accused the network of "sheer dishonesty" over its conduct.

“[The BBC] have yet to apologize for what truly matters here: the incredibly serious falsification of bank statements suggesting that Diana’s closest confidants were spying on her for her enemies," Spencer told PEOPLE exclusively earlier this month.

Amanda Edwards/WireImage; Tim Graham Photo Library/Getty Charles Spencer and Princess Diana

"This was what led me to talk to Diana about such things. This in turn led to the meeting where I introduced Diana to Bashir, on 19 September 1995. This then led to the interview," he continued. "The BBC have so far refused to acknowledge the above. They claim Diana wasn’t misled. They have ignored my inquiry as to whether the apology over their false bank statements extends to the ones that actually persuaded Diana to meet Bashir.”

RELATED: Princess Diana's Brother Charles Spencer Shares Rare Childhood Photo of the Late Royal

Last week, the BBC reiterated that the organization had apologized to Spencer, telling PEOPLE, “The BBC has apologized. We are happy to repeat that apology. And while this was a quarter of a century ago, we absolutely will investigate — robustly and fairly — substantive new information. We have asked Earl Spencer to share further information with the BBC. Unfortunately, we are hampered at the moment by the simple fact that we are unable to discuss any of this with Martin Bashir, as he is seriously unwell. When he is well, we will of course hold an investigation into these new issues.”

Alan Davidson/REX/Shutterstock Princess Diana and Rosa Monckton

Princess Diana's close friend Rosa Monckton — who chose Diana as a godmother for her daughter — told the Daily Mail that the interview contributed to the royal's untimely death.

Monckton wrote that the interview "dishonestly achieved, probably changed the course of history," prompting Princess Diana and Prince Charles to begin divorce proceedings, "which meant that decisions about their future were made hurriedly, with long-term implications not thought through."

"Among those decisions was the fact that Diana lost her royal title," Diana's friend said. "Had she retained it, she would have still been in the embrace of the Royal Family when in Paris on August 31, 1997. And she would almost certainly not have been in the incapable hands of a speeding drunk driver employed by Mohamed Al-Fayed, who owned the Ritz Hotel where she and his son, Dodi, had dined."

The car accident that killed Diana is believed to have been caused by paparazzi chasing the royal — but Monckton said the BBC is equally responsible.

"For the BBC, our national broadcasting corporation, to behave in this devious and underhand way is just as bad as any of the hunting pack of paparazzi," she said.

Tim Graham/Getty Prince Charles and Princess Diana

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In response to the Sunday Times story last month, the BBC said Bashir is unwell and unable to respond: “Questions surrounding Panorama’s interview with the Princess of Wales and in particular the ‘mocking-up’ of bank statements, were covered in the press at the time. BBC records from the period indicate that Martin had explained to the BBC that the documents had been shown to Earl Spencer, and that they were not shown to the Princess of Wales. The BBC’s internal records from the time indicate that Martin had met the Princess of Wales before the mocked-up documentation existed. These accounts also say that the Princess of Wales confirmed in writing that these documents played no part in her decision to give [the interview].”

On Monday, the BBC announced that they will hold a “robust and independent investigation.”