A Queensland-based man who believes he is the illegitimate son of Prince Charles and Camilla Parker-Bowles has launched legal action against the Prince's official royal estate, in a bid to confirm the paternity.
Simon Charles Dorante-Day, 53, believes he lived with Camilla until he was about 18 months old, and was then adopted out to his parents, Karen and David Day.
Dorante-Day says Charles and Camilla met in 1965 and he was born the following year, after a period of nine months during which Camilla "disappeared" and Charles was sent off to Australia.
The man's adoptive grandparents, Winifred and Ernest, worked for the Queen and Prince Philip and were allegedly well respected and trusted within the Royal Family.
"My grandmother, who worked for the Queen, told me outright that I was Camilla and Charles' son many times," he told New Idea.
The engineer, born in England, says there are other strange details about the time he was born. The hospital where he was told he was born did not deliver babies at that time. Moreover, the parents' names on his birth certificate turned out to be fictitious.
He says he, not William, is second in line to the throne.
Dorante-Day has filed legal proceedings in Australia's High Court to prove he is Charles and Camilla's son and the case is currently being assessed, he says.
"This is most explosive thing that's ever happened to the palace," he said.
"It's definitely the most significant step I've taken so far – I've had to force a deadline, hold them to a date, because we need answers."
Court staff reportedly laughed it off when he first filed papers but the man is adamant his "40-year search" will lead him to the truth.
Dorante-Day says the royal family would have found out about the court case before Christmas and has no doubt it came up during Megxit negotiations.
"While the whole world was thinking they were talking about Harry, we believe this legal battle would've also been on the agenda and discussed," he said.
Clarence House told the Mirror they "did not have any comment to make on the story".