When the Prince of Wales married Camilla in 2005, the Duchess of Cornwall had an incredibly tense relationship with the Duke of York.
Tom Bower, Charles biographer, the royal couple believed Prince Andrew had been speaking ill of Camilla to Queen Elizabeth II and Prince Philip.
"Mindful of Diana’s prediction on Panorama that he would never be King, Charles convinced himself that even Princess Diana and Sarah Ferguson, were hatching plans to replace him as heir," wrote Mr Bower in his 2018 biography.
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Mark Bolland, the future king's spin doctor, told the author, "Andrew wanted to be me.
"I should have let him work with me. Now he’s unhelpful."
In addition, an insider told the Daily Mail that the Duchess "hasn't forgotten" how "deeply unhelpful" Andrew was when she was joining the Royal Family.
According to the insider, "Camilla has always felt Andrew could have done more.
"The Queen listens to Andrew and he could have helped his brother at a time when he had few allies within the family.
"In fact, I would go so far as to say he was deeply unhelpful when support would have meant a huge amount to her and the Prince.
"Looking back to when there was little public sympathy for Charles and Camilla, if not open hostility, it was a case of Andrew playing politics. Camilla hasn’t forgotten."
Prince Charles allegedly accused his younger brother Prince Andrew of "spreading poison" about his wife Camilla Parker Bowles prior to their marriage.
Apparently, the feeling goes both ways between the brothers.