Diana ‘told newspaper editor her marriage to Charles was hell from day one’

Diana, Princess of Wales told a national newspaper editor her marriage was "hell from day one" and that she "hated" the Prince of Wales as she sought to make her story public, a documentary claims.

A Channel 4 film about Diana's bombshell interview with the BBC's Panorama programme claims the royal also told the then editor of The Daily Telegraph, Sir Max Hastings, Charles was not up to the task of kingship.

Diana: The Truth Behind The Interview, which will be screened on Wednesday, examines the circumstances behind the princess's interview with BBC broadcaster Martin Bashir.

According to the documentary, the BBC was Diana's second choice to tell her story, as three months before the Panorama interview she attempted to get her story out in a two-hour, one-on-one briefing with the then Daily Telegraph editor.

The programme claims Diana told Sir Max that she "hated" Charles and that the marriage "had been hell from day one".

She is said to have branded the prince not up to the task of kingship and said that their son the Duke of Cambridge should be the next king, and that she was the target of an assassination plot.

According to the documentary, Sir Max declined to publish, saying that Diana appeared vulnerable and impressionable and that her interests were best served if issues were not exposed while the couple worked through their problems in private.

Diana and Charles on their wedding day. PA Wire
Diana and Charles on their wedding day (PA)

At the time of her death in 1997 in a Paris car crash, the princess had been divorced for a year after the final stages of her marriage break-up had become public.

Diana's marital troubles – and issues such as her bulimia and suicide attempts – had been laid bare in the 1992 Andrew Morton book Diana: Her True Story.

Three years later came more revelations when she told the BBC Panorama documentary: "Well, there were three of us in this marriage, so it was a bit crowded," a reference to Camilla Parker Bowles – who the Prince of Wales later married.

In 1994, Charles had confessed to adultery in a TV interview with broadcaster Jonathan Dimbleby, but only after his marriage had "irretrievably broken down".