Princess Diana would not have been "ecstatic" about daughter-in-law Meghan Markle, and the two women may have clashed due to their similar personalities, according to Lady Colin Campbell.
The 69-year-old Jamaican-born socialite, who has published three books about the British Royal Family including a biography on the late princess, added she would have 'lived with' whatever made her children to be happy.
She spoke more favourably about the Duchess of Cambridge, suggesting Diana would have approved "wholeheartedly" of son Prince William's choice of wife.
Speaking to new! magazine, Lady Colin explained: "I think Meghan and Diana are sufficiently similar personalities for there to have been the potential for conflict.
"They have very similar personalities, which would make me believe trouble may well have brewed down the line."
She added that they share many of the same traits, quipping: "It's no accident that Meghan's an actress and everyone called Diana the actress."
Lady Colin, who is set to appear on the new series of Celebs Go Dating alongside Lauren Goodger and Megan Barton-Hanson, claimed the Duchess of Sussex "wanted to become a princess" and "sought it out".
"I hope she fulfils the tremendous expectations," she said, adding that royal family members marrying "commoners" encouraged non-regal women to target princes "for the platform".
"They want perpetual stardom scripted by themselves," she went on. "With some it works well, with others the results are more mixed. Let's say the jury's out."
She previously told the Irish Independent that Meghan is "much better educated and more academic" than Diana, and "almost disturbingly self-confident".
Having also identified their "discomforting parallels", Lady Colin added: "We must hope that Meghan has no psychological instability - as Diana had - and won't hit the buffers at any point, as Diana did."
Speaking about the Duchess of Cambridge, Lady Colin said she was doing a "superb" job and "can't be faulted in her performance or demeanour".
Earlier this year Lady Colin, who was a confidante of Princess Diana and still has close royal connections, claimed Meghan has "considerably changed" Harry, who is "besotted" by her.
Speaking in the Channel 5 documentary Kate V Meghan: Princesses At War, Lady Colin revealed that the Duke of Sussex is "beguiled" by his new wife.
The documentary also claimed that while Harry is happier than ever since settling down with Meghan, things between him and Prince William are more strained.
While rumours of a feud between Meghan and Kate have swirled, the show claimed that the rift was actually between Harry and William - after the younger brother felt "criticised" for his choice of wife.