An Australian man who has repeatedly claimed that he is the love child of Prince Charles and his wife Camilla, has now come up with a piece of photo evidence to prove his theory.

Prince Charles has two sons, Prince William and Prince Harry, from his previous marriage to Princess Diana. Camilla also shares two children, Laura and Tom, with ex-husband Andrew Parker Bowles. The future monarch couple does not have any children together, but British-born engineer Simon Dorante-Day, who settled in Australia after being adopted, is convinced that he is their biological child.

In a recent appearance on Seven Network's breakfast program "Sunrise," Dorante-Day shared a picture of his 14-year-old son Liam, comparing it to an old photograph of a young Queen Elizabeth II, insisting that the resemblance proves that the two are related. If Dorante-Day's claims are believed to be true, he is the eldest grandson of the Queen and his son is her great-grandson.

"I think the evidence speaks for itself," Dorante-Day told hosts David Koch and Natalie Barr on Tuesday morning, showing his son's picture which was clicked last week while on a fishing trip at Bribie Island in Queensland. He informed the hosts that he had shared the original picture on his Facebook account after which a follower changed it into black-and-white and rotated it and put it alongside the Queen, reports Mail Online.

"I said every day, when I get up in the morning and the kids speak to me, the first thing I see when I turn around, is that, so it is always in my face," he added.

Dorante-Day was adopted by British couple Karen and David Day near Portsmouth in April 1966, when he was 18-months-old. He claims that his adoptive grandparents, Winifred and Ernest, worked for the Queen and her late husband Prince Philip as a cook and a gardener respectively and told him "many times" that he was "Charles and Camilla's child."

However, royal experts believe that Charles and Camilla came into contact in the 1970s, years after Dorante-Day was conceived. When questioned about the contradiction, Dorante-Day said: "Just because your grandmother said it doesn't mean you are going to believe it. I did do my research, so the timelines are gaps, people need to come forward and come clean. I have a lot of evidence and I'm slowly collecting more."

Prince Charles and Camilla
Prince Charles, Camilla. Photo: Getty Images/Chris Jackson