The shocking revelation was made by Diana's former butler Paul Burrell, who came forward in Smithsonian Channel's newest documentary 'Princess Diana's 'Wicked' Stepmother,' which shines a light on her stepmother Countess Raine Spencer and how she also had a lasting impact on Diana before her death in 1997 at the age of 36, reported Fox News.

In the special documentary, fans can catch a glimpse of all the interviews of people who were close to the princess along with close friends and staff of both women.
According to Fox News, the 61-year-old butler served as a footman to Queen Elizabeth II before he began working for Diana in 1987 until her death a decade later.
While the documentary focuses on the rivalry between Diana and Spencer, it was the royal's relationship with her mother, Frances Shand Kydd, that will leave audiences stunned.
Burrell told Fox News that he could never forget Diana's last conversation with Shand Kydd.

"I was in my little pantry underneath the main staircase of Kensington Palace and I could hear this sobbing coming out of [Diana's] room," claimed Burrell. "Then she shouted, 'Paul, please come. Come quick.' So I ran up the staircase, and I found the princess crumpled in the middle of her room with the telephone to her ear, and she beckoned me to come closer. I could hear what her mother was saying. She said, 'Listen. Listen to what mummy's saying.'

"Mrs. Shand Kydd had had a few to drink that night," Burrell continued. "She was berating the princess and then calling her a whore. She said, 'That's what you are. I've raised a whore, whoring around town with Muslim men. You should be ashamed of yourself.' Diana was sobbing, saying 'Mummy, please don't say those words to me. Please don't call me those names.' She begged her. She kept begging her not to say it.

"Of course, she's repeating it in her drunkenness. Diana eventually said, 'I'm going to put the phone down and I'll never speak to you again.' And that's exactly what she did. She never did speak to her mother again."

The butler claimed that the late Princess of Wales Burrell claimed Diana broke off her relationship with Shand Kydd after the phone call.