Royal biographer Tom Bower has shed some light on the scandalous affair in his book Rebel Prince: The Power, Passion and Defiance of Prince Charles, claiming Camilla initially referred to Diana as a "mouse" when Charles began courting her.
Following the collapse of Diana and Charles' marriage in the nineties, the news of the affair became public knowledge, and Camilla was widely vilified by the public.
Diana, in a 1995 BBC Panorama interview, famously said: "There were three of us in this marriage, so it was a bit crowded".
Diana's very public outpouring of emotion over her husband's infidelity forced Camilla to retreat from the public view for almost a year. It was that interview that lead to Camilla dubbing the people's princess a 'mad cow', according to Bower.
Charles has since admitted that his affair with Camilla started in 1986.
Bower writes that of that time Camilla had the opportunity to stand back and allow Charles and Diana a shot at a happy marriage but "instead, she coldly pushed her rival aside”.
Mr Bower claims Camilla insinuated Diana was having multiple extramarital affairs and would defend herself in private by stating she was only guilty one extramarital lover.
Prince Charles and Princess Diana were married in 1982 and divorced in 1996.
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