A man who claims to be the illegitimate son of Prince Charles and Camilla Parker Bowles believes his child resembles the Queen. Aussie Simon Dorante-Day, 55, claims he was conceived in 1965, when the royal couple first became romantically involved as teens.

Simon Dorante-Day, an engineer born in the United Kingdom (UK) and now residing in Australia, recently uploaded three pictures on Facebook: one of his kid and two of Queen Elizabeth II – one shot when she was younger and another more recently.

He obviously encouraged people to notice a familial connection between his adolescent boy’s grin and that of England’s queen by captioning the picture “uummmm an interesting comparison.”

“I’ve never seen anyone so alike!!!!!! Wow” Vicky Faraday said.

“Wow, I can’t get over how alike they are, it’s amazing,” Namh Moloney said.

Another said that the adolescent was “the queen’s double in her older years.”

Simon Dorante-Day claims the Duke and Duchess of Cornwall are his birth parents (Image: Simon Dorante-Day/Facebook)

Dorante-Day’s adopted grandparents, Winifred and Ernest, worked as a chef and gardener for the Queen and Prince Philip, according to various media sources.

Simon initially made the outrageous allegations in 2016 and has posted many side-by-side pictures of himself and his son compared to the Royals.

He is now dead serious about it, and has even filed documents in the High Court to compel the Duke and Duchess of Cornwall to submit to a DNA test.

“I believe you. This isn’t about claiming a throne…,” said another online user.

“Everyone should be entitled to trace their biological connection. I hope the truth does come out. You definitely have Camilla’s eyes!”

Simon previously said that the Royal Family has spent “years” concealing the “truth.”

Dorante-Day posted a follow-up montage last week, which included a photo of himself close to Prince William (who, if his claims were true, would be his younger half-brother).

Dorante-Day claims that the appropriate authorities have been aware of his allegation for more than 23 years.

“I’ve said this before, but some people aren’t listening, so I’ll say it again! I have a LEGAL right to pursue my True Identity – not to be lied to and deceived,” he said in June.

“Firstly, the authorities (and by that, I mean Monarchy, Government, Health Departments and Police) both in Australia and in the UK have been aware of my claims, and my issue, since at least 1998 when I first asked for my adoption paperwork. So, they know, and have been across every detail, and all involved”

The Palace has never replied to Simon’s accusations, but he is not giving up.

“I’m always getting recognised,” he told 7NEWS.com.au

““I got photographed by another passenger on a train, on my way to Family Court. He was even videoing me at one point.”

Prince Charles and Camilla have never responded to Simon Dorante-Day’s claims. Credit: Getty/Supplied

Simon even claimed that Princess Diana was aware of his existence and was prepared to disclose what he claims she was aware of before to her sad death in 1997.

Dorante-Day says his grandma informed him unequivocally that he was Charles and Camilla’s son. He thinks he was conceived when the royal couple were 17 and 18 years old, respectively.