When Dorante-Day shared the photo with his Facebook followers, many were stunned by the "undeniable" resemblance.
"Wow you look like Andrew. I had to look three times," one wrote.
"Wow, I thought this was Prince Andrew," another said.
He has shared multiple pictures comparing himself and his family to royal members, including an image of his son Liam next to a photo of the Queen in her 20s.
Dorante-Day said he also remembered being teased for having big ears as a child but claims he must have had surgery when he was young to get them pinned back as photos show they are "definitely different" now.
Prince Andrew. Photo / Supplied
The royal family has never responded to Dorante-Day's claims but he is so confident he is preparing to take the couple to court in order to demand a DNA test in the coming months.
The photo Simon Dorante-Day shared of himself in 1990, which he said looks a lot like Prince Andrew. Photo / Supplied
He has said his belief that Charles and Camilla are his parents are not based on photos.
Here is a list of everything Dorante-Day has offered as proof of his royal lineage:
The many comparison photos:
Over the years, Dorante-Day and his followers have created multiple comparison photos they believe show remarkable similarities between his family and the royals.
The 55-year-old claimed his adoptive grandparents, Winifred and Ernest, worked as a cook and gardener for the Queen and Prince Philip.
He said his during his childhood his grandmother repeatedly told him he was Prince Charles and Camilla's son.
"She didn't just hint at it, she told me outright," Dorante-Day previously said.
Dorante-Day was adopted by a local couple named Karen and David Day when he was 8 months old.
He previously claimed Camilla had kept him until that time but the adoption was arranged through his adoptive grandmother when he started to get too old.
The couple's murky timeline and Camilla's brief social scene absence:
Dorante-Day has spent years researching the royals and the timeline of Prince Charles and Camilla's relationship, saying the dates for when they first met change depending on the source of the information.
He claims he was conceived by a in 1965 by a 17-year-old Charles and 18-year-old Camilla.
Prince Charles pictured in May this year. Photo / Getty Images
"One of the first things we did was get all the biographies that we could at the time and look this thing up and look at the times to see where Charles and Camilla were, who otherwise could be involved," he told Sunrise this week.
"I did do my research, so the timelines are gaps, people need to come forward and come clean."
He said his research led him to discover that in the months leading up to his birth Camilla disappeared from the UK social scene for at least nine months,n while Charles was sent to Australia.
Dorante-Day also revealed he has recollections of being taken to houses around Portsmouth as a young boy where he would spend time with a woman he believes was Camilla. He said protection officers and his adoptive parents would wait outside during these visits.
Dorante-Day told Sunrise his birth certificate is "complete rubbish" and said the documentation he has from his adoption is written in his adoptive mother's handwriting.
He said there are "lots of bits of evidence" like this that he needs to prove through avenues like handwriting analysis.
The Prince of Wales with Prince Harry and Prince William after their Highgrove team had beaten Cirencester Park in The King Constantine Cup 2002. Photo / Getty Images
"I have a lot of evidence and I'm slowly collecting more. The longer this thing runs the more they are going to get it on their face, not me," he said.
He also claimed the hospital listed on his birth certificate didn't deliver a single baby during the decade he was born.
He also believes the names the parents listed on his birth certificate were "fictitious".
