“She is wrong for us, she is wrong for the country, she is wrong for the job.’ Well, it’s turned out to be true.”
Lady C also alleged the Queen’s second child and only daughter accused Meghan of “flagrantly attention-seeking”.
“It just absolutely turned Princess Anne off,” she said.
The royal author also spoke on Meghan and her husband Prince Harry’s claims of racism against a member of the Royal Family during their Oprah Winfrey interview last month.
Lady C insisted the Royal Family are entirely not racist, as she said there were “no concerns” over Meghan’s biracial heritage.
She continued: “No one is the guilty party in terms of racism.”
Meghan told Oprah: “They were saying they didn’t want him to be a prince or princess, which would be different from protocol, and that he wasn’t going to receive security.
“This went on for the last few months of our pregnancy where I was going, hold on for a second.”
According to the Duchess, the decision for Archie not to have a title nor security was made in tandem with “concerns and conversations about how dark [Archie’s] skin might be when he’s born”.
A statement added Harry and Meghan would always be “much loved” by the family.
Prince William told reporters the Royal Family was “very much not racist”.
Lady C was previously married to Lord Colin Ivar Campbell, son of the 11th Duke of Argyll and has written a book on Princess Diana before.
Buckingham Palace declined to comment on the video when approached by The Mirror.
The Daily Express has contacted representatives of Meghan and Prince Harry for comment.