Australian man who claims to be Prince Charles and Camilla's son shares photo evidence

The man has been in a decades-long battle to prove he is the secret child of Prince Charles and Camilla, Duchess of Cornwall. Photo / Simon Charle Dorante-Day / Facebook

An Aussie grandfather has shared new photos as part of his decades-long battle to prove he is the secret child of Prince Charles and Camilla, Duchess of Cornwall.

Queenslander Simon Dorante-Day, 55, who was born in the UK, claims he was conceived in 1965. He says it was at this time that the heir to the British throne and Camilla were first romantically linked.

Dorante-Day believes the couple conceived him when Charles was just 17, and Camilla 18. The father-of-nine was born in April 1966 and adopted in Portsmouth, England, by a family with links to the Queen.

"My grandmother, who had worked for the Queen, told me outright that I was Camilla and Charles' son many times," Dorante-Day said in an interview with 7News.

Prince Charles and Camilla have not responded to the claims.

Dorante-Day has about 7700 followers on his Facebook page, and is supported by legal aides and his wife, Dr Elvianna Dorante-Day.

Simon shared this side-by-side image of his son and the Queen. Photo / Facebook

This week, he shared a new image comparing his son Liam to the Queen when she was in her 20s.

He said he was "blown away" when he first saw the images.

"Elvie and I feel like we see many members of the royal family in our children, but this one was an eye opener," he said.

Dorante-Day shared the image on his Facebook where it received hundreds of reactions and comments.

"Yes can see resemblance. Also lots of other people from all sides. Prince Philips family. Also the royal family. I think you have same type of features as Philip," one woman wrote.

Simon shared this side-by-side image of his son and the Queen. Photo / Facebook

"It would be wonderful if it came out. It would be good not bad. The people would be on side."

"Probably embarrassing for the Monarchy and it wouldn't be a 1st time by a long shot," one man said.

"Yes, I saw the resemblance of Liam to Elizabeth in the photo you shared today and thought, wow," another said. "Too many similarities between yourself, your children and others for it to be a mere coincidence or conspiracy theory."

Dorante-Day told New Idea in 2019 he believes his truth would never have been revealed if it wasn't for the death of Princess Diana in 1997.

"We believe that Diana knew of my existence and that she had put the pieces together," he said.

"I think Diana was at a point where she was finding out answers about her life, how she was wronged, and she was going to go public with it."