Princess Diana recorded tapes detailing her true feelings about her marriage to Charles (Image: Getty)

       Princess Diana's intimate thoughts and feelings about her marriage to King Charles and his “disappointment” that Prince Harry was not a girl have been revealed in previously unheard tapes.

       The late royal secretly recorded the clips in the 90s to send to author Andrew Morton, who used them to write the bestselling book, Diana: Her True Story.

       Snippets of the tapes, which are set to air in a documentary next year, have been released in the US and show Diana discussing her husband, her sons and the troubled relationship she had with her stepmother Raine Spencer.

       In one of the tapes, Diana brands her July 1981 wedding to Charles when she was 20 years-old as "ridiculous".

       She said: “It was grown up. Here's Diana, a kindergarten teacher. I mean the whole thing was ridiculous.”

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       She also spoke at length about her strained relationship with her stepmother Raine, who married Diana's father John in 1976, and revealed that Charles fell out with her at Harry’s christening in 1984.

       Diana claims that Charles told Countess Spencer: “We're so disappointed, we wanted a girl.”

       She responded by “snapping his head off'”and telling him he should “realise you are lucky to have a child”, Diana added.

       Diana’s parents divorced in 1969, when she was just six-years-old. Diana and her siblings never fully accepted Raine into the family, and famously nicknamed her Acid Raine and sang: "Raine, Raine, go away!"

       Princess Diana and Charles married in 1981 (Image: Getty)

       In one of the tapes, Diana details their strained relationship, and said: “I was so angry. I said I hate you so much. If you only knew how much we all hated you for what you've done. You ruined the house.

       “You spent daddy's money. I have said everything I possibly could. Raine said you have no idea how much pain your mother put your father through.

       “I said pain Raine? It’s one word you don’t even know how to relate to. In my job I see people suffer like you never see. You call that pain? I said you've got a lot to learn. I remember really going for her gullet.”

       But following Diana's father's death, their relationship began to thaw and they started to meet up regularly.

       In one of the tapes, Diana details their strained relationship, and said: “I was so angry. I said I hate you so much. If you only knew how much we all hated you for what you've done. You ruined the house.

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       The upcoming documentary is a follow-up to 2017 production Diana: In Her Own Words.

       Tom Jennings, the producer of both documentaries, told ABC: “When the first film came out, people were blown away because they had not heard Diana talk like this before.”

       He added: “It is important as part of Diana's legacy to allow more of those tapes to be heard.”

       But the release of the tapes in 2017 - to coincide with the 20th anniversary of Diana’s death - sparked furore from some of Diana's friend's and former employees who said sharing them violated Diana's privacy as they were never meant to be released to the public.

       Princess Diana discusses her marriage to Charles in the tapes (Image: Getty)

       Diana’s brother, Lord Charles Spencer, claimed the tapes belonged to the family and waged a lengthy legal battle to prevent the tapes' public release.

       But the tapes were returned to Diana’s voice coach Peter Settelen, who was deemed the rightful copyright owner by the courts.

       They were later sold to American broadcaster NBC for an undisclosed sum

       Diana recorded seven hours of audio while she was still married to the then-Prince of Wales which she sent to Morton.

       His book painted a stark contrast to the couple’s carefully crafted image that they were happily married, as Diana opened up about her intense unhappiness, self-harm and struggle with bulimia.

       The revelations were so stark that many bookstores banned it, unaware that Diana was the source behind the work.

       Diana’s brother, Lord Charles Spencer, claimed the tapes belonged to the family and waged a lengthy legal battle to prevent the tapes' public release.

       But the tapes were returned to Diana’s voice coach Peter Settelen, who was deemed the rightful copyright owner by the courts.

       They were later sold to American broadcaster NBC for an undisclosed sum

       Diana’s brother, Lord Charles Spencer, claimed the tapes belonged to the family and waged a lengthy legal battle to prevent the tapes' public release.

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