According to royal biographer Tom Bower, the Prince of Wales developed a highly "combustable" relationship with his sister who has been described as "stubborn and strong-willed" while Charles is widely regarded as "defensive and meek".
The Express UK reports that in an explosive row between the royal siblings, Princess Anne lashed out at Charles condemning him for his long-running affair with Camilla Parker-Bowles during his marriage to Diana, Princess of Wales.
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But Charles did not take the Princess Royal's criticism lying down, with Bower writing of how he swiftly retorted: "She's one to talk!"
Prince Charles was referring to the scandalous relationship Anne enjoyed with Andrew Parker-Bowles in the early 1970s - while he was dating Camilla, now Duchess of Cornwall.
Royal expert Penny Junor has previously said Camilla may have never struck up a romance with Prince Charles if her then-boyfriend had not embarked on an affair with the Princess Royal first.
Junor, who is widely regarded as a reliable source, claimed that Camilla planned to teach her "cheating boyfriend a lesson".
The author has gone so far as to claim "it was Princess Anne, not Camilla, who inadvertently caused the breakdown of Diana and Charles' marriage".
Fellow royal writer Phil Dampier believes Junor's story may be true, and has confirmed that Parker-Bowles and Princess Anne remain very close friends.
He told IBTimes UK: "I have read this before and it wouldn't surprise me. Anne and Andrew Parker Bowles were very close – they still are!"
In recent years, Princess Anne and Andrew Parker-Bowles, - who share a lifelong love of horse racing - have been photographed together at events such as the famed Cheltenham festival.