Prince Charles and Camilla’s 'secret son' says he'll 'prove it' in brave next move

An Australian man who believes he is the secret son of Prince Charles and Camilla, Duchess of Cornwall, will take the fight to prove his identity, it has been claimed.

Simon Dorante-Day was adopted into a family who had ties to the Queen and lived in Portsmouth, England, when he was a kid.

The 55-year-old told 7News his late grandmother, who used to work for the Queen, told him "outright" that he was Camilla and Charles' biological son "many times."

He claims to have been given evidence that shows Camilla became close with Charles in 1965 when the pair were teenagers.

Camilla then allegedly disappeared from Britain's social scene for 9 months while Charles was sent to Australia.

Dorante-Day is now preparing to take the fight for his identity to the Australian High Court.

He told Sunrise on Tuesday April 27 there's "lots of bits of evidence" that have "to go before the court".

The Aussie also moaned that it is "unfair" that he "constantly" has to "right" the truth, claiming Camilla, Charles and the Royal Family "know the truth."

"The documentation that I’ve got for the adoption is written in my own adopted mother’s handwriting.

“So there’s lots of bits of evidence like this... that have got to go before the court.

“It’s just unfair that I constantly have to fight this when really, they know the truth,' he said.

Dorante-Day added: "My birth certificate is complete rubbish.

"The longer this thing runs, the more they’re going to get egg on their face, not me.

"My grandmother, who had worked for the Queen, told me outright that I was Camilla and Charles’ son many times."