Princess Diana was an iconic figure, a well-beloved member of the British royal family who changed the way royals approach the public. Because of that, she gained the moniker "People's Princess."
After her marriage with the heir to the throne Prince Charles in July 1981 at St Paul's Cathedral in London, she evolved into the perfect queen consort.
She became the nation's sweetheart by breaking barriers of socially acceptable standards -- from raising awareness about mental illness to her famous photograph where she was seen shaking the hand of an AIDS patient.
Princess Diana "Not Welcomed" By The Royal Family
Despite her efforts, the Princess of Wales revealed that she felt like "an outsider" and "unwelcomed" by the royal family.
Following her controversial and tumultuous relationship with the Prince of Wales, the two separated in 1992 and divorced in 1996 after their 15 years of marriage. However, Princess Diana remained cordial to the rest of the family and even continued to visit Sandringham House in Norfolk during the holidays to be with her two sons, Princes William and Harry.
With this, one royal expert claimed that the Queen Mother was bitter to the mother-of-two during her first Christmas after the separation.
In Channel 5's documentary "Diana, In Her Own Words," royal expert Richard Kay pointed out that the Princess of Wales "was not welcome at Sandringham."
"I remember her telling me the first occasion she went, the Queen Mother has sort of looked at her, raised her eyebrow and said, 'I didn't think we'd see you again," he explained.
Kay mentioned that Diana had always had a "tough character" but endured all the pain for her kids.
"Under that kind of pressure, you have to be quite a tough character and I think she found it extremely hard but she took a deep breath and she got through it," the expert added.
The "Terrifying" And "Disappointing" Experience of Princess Diana at Sandringham
In her explosive 1992 tell-all book "DIANA: Her True Story," Princess Diana revealed to British royal reporter Andrew Morton that her experience at the Norfolk residence was "terrifying and so disappointing."
"Christmas at Sandringham was highly fraught. Terrifying and so disappointing. No boisterous behavior, lots of tension, silly behavior, silly jokes that outsiders would find odd, but insiders understood. I sure was an outsider."
Aside from the Queen Mother, Prince Charles' sister, Princess Anne, was said to be not a fan of Diana as well.
During her first Christmas at Sandringham, the Princess of Wales was not informed about the gag exchange gift tradition of the family.
"The rule is, the jokier the better," royal author Claudia Joseph explained.
Instead, she gave the Princess Royal a serious gift, which annoyed Princess Anne.
"I think they compete to out-do each other in terms of the joke. Princess Diana was obviously not briefed of this little quirk of the royals. She gave Princess Anne a cashmere jumper thinking that that was a suitable present for her sister-in-law. And in exchange, she received a loo-roll holder! Obviously, the young princess was humiliated," the royal author mentioned.
In previous royal family news, biographer Ingrid Seward said in her 1995 book that Prince Edward claimed that Princess Diana and her relationship with her sister-in-law was strained.
"Anne was indifferent to Diana from the very beginning. She treated the woman, who by marriage to her elder brother might have become her Queen, with withering disdain," Seward added.