Princess Diana's relationship with the woman who married her beloved father Earl Spencer has never been any secret.
But now a new documentary has revealed the shocking depths of the late royal's feud with her stepmother Raine Spencer. Things became so strained between them that Diana even pushed her stepmother down the stairs.
In Diana's Wicked Stepmother, which airs tonight in the UK, the countess' personal assistant revealed that Diana flew into a rage with Raine for not paying enough attention to her mother Frances Shand Kydd in the ancestral home.
Raine's personal assistant Sue Howe recalled how she was covered in bruises: "She was badly bruised and dreadfully upset. It was not justified at all, it was a cruel heartless thing to do and I think it was Diana's perception of how Raine was treating Mrs Shand Kidd.
Raine was always considered an unwelcome addition to the family by the Spencer children. Photo / Getty
"I think Diana was very stressed. This sounds really wrong but she wasn't centre of attention on this occasion."
Raine Spencer married Diana's father Johnnie, the 8th Earl Spencer in July 1976, and was hated by his children, who nicknamed her "Acid Raine". However, the two women eventually made amends after Earl Spencer died in 1992, and Diana thanked Raine for all the "love" she had shown Johnnie.
Raine was hosting Charles Spencer's wedding at Althorpe in 1989 when she came to blows with Diana, who attended with her mother Frances Shand Kydd.
According to royal experts, Diana became frustrated that Raine wasn't being attentive enough to Frances at lunch and flew at her in a rage, pushing Raine down the stairs.
Royal biographer Ingrid Seward said: "She had a furious row with Raine because Diana was so upset that her own mother had been ignored in the ancestral home. She pushed her and Raine fell down the stairs."
In 1978 Johnnie collapsed and suffered a stroke, and tragedy struck again when caught a serious infection while in hospital, which saw him slip into a coma.
Raine was at his bedside but prevented his children from seeing him, insisting she should be the one to nurse him back to good health.
Biographer Penny Junor said: "She set up a vigil at his bedside and she was there day and night but she was very territorial about him, she was fighting for his life. She felt that he did not need to have his children there.
"She met Johnnie, who was recently divorced from [Diana's] mother Frances Shand Kydd, at a cocktail party when she was still married to her first husband Gerald Legge, the future 9th Earl of Dartmouth.
"Raine came as an unwelcome addition to the Spencer family, and was often ganged up on by the children."
Seward said: "All the Spencer children behaved very badly to Raine, it wasn't just Diana. They were purposely ganging up on her."
After moving into Althorpe, the Spencer's ancestral home, Raine began to redecorate, selling antique furniture that had been owned by the family for hundreds of years and gilding picture frames in bright gold paint.
"When children found out what Raine was doing at Althorpe they loathed her even more and they did try and stop her. They talked to their father but I think he was scared of not supporting Raine because he needed her so much at every level of his life," Raine's biographer Angela Levine said.
Raine was invited to Diana and Princess Charles' wedding but was kept at the back of Westminster Abbey and when Johnnie died in 1992 she was kicked out of Althorpe by Charles with her belongings in black bin liners.
Charles and Diana on their last official trip together. Photo / Getty
Thirteen months after she was removed from the Spencer family home she married her third husband Count Jean-Francois Pineton de Chambrun, but the marriage lasted just three years.
The two Spencer women were not to be at war forever: after Charles and Diana divorced in 1996 Diana made the surprising move of inviting Raine to dinner at Kensington Palace.
"Diana was fully aware of what she was doing, she knew that this was a U-turn day. She knew the Spencer family would not be very happy but she couldn't care less because she thought it was time Raine came back," Diana's butler Paul Burrell said in the film.
Diana was said to have started crying, thanking Raine for the love she had shown her father when he was alive and the two women hugged.
For the last year of Diana's life the pair remained very close and spoke on the telephone every morning, before Diana died in Paris in 1997. Raine died in October 2016 after a short battle with cancer.
