PRINCE Andrew "lobbied hard" to stop Charles from becoming king, an explosive new book has claimed.
He is also said to have tried to turn Queen Elizabeth against his brother's partner - and appeared "very angry" that he couldn't "rule the country in some way".
Citing a "senior insider" in Camilla, Duchess of Cornwall: From Outcast to Queen Consort, Ms Levin writes: "Andrew lobbied very hard with the hope that Charles would not become king when his mother died, and that William would wear the crown."
A senior insider at the palace is also said to have told her when Princess Diana was alive, she plotted with Andrew - through her friendship with Sarah Ferguson - to try and push Charles aside.
The source said: "They were dark and strange times, where paranoia became reality, and this was a worry.
"His behaviour was very, very negative and extremely unpleasant to Queen [Elizabeth], who disagreed. I was told it was one of the rare occasions he didn't get his way."
They added: "Nonetheless, he was apparently very angry that he couldn't rule the country in some way.
"He remained so hostile to Camilla's emergence and acceptance that it's doubtful it has ever been forgiven."
In the extract of the book, serialised in The Telegraph, Angela Levin goes onto write about Andrew's alleged hostility toward Charles marrying Camilla - claiming the duke was "poisonous" and "very nasty" about her to Queen Elizabeth.
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According to the biographer's sources, Andrew's claims included that she was insufficiently aristocratic and "not to be trusted".
Royal sources said the late monarch made the decision in recognition of Camilla's hard work as well as the happiness she brings her son.
And in a statement marking her accession earlier this year, the Queen said: “I remain eternally grateful for, and humbled by, the loyalty and affection that you continue to give me.
“And when, in the fullness of time, my son Charles becomes King, I know you will give him and his wife Camilla the same support that you have given me.
“And it is my sincere wish that, when that time comes, Camilla will be known as Queen Consort as she continues her own loyal service.”
Representatives for Prince Andrew declined to comment.
Buckingham Palace has been approached for comment.