An Australian man who believes he is King Charles’ ‘secret son’ has made a wild claim that a four-way paternity test should be done in a bid to prove his claims.

British-born Simon Charles Dorante-Day has made headlines around the world over unproven claims he is the illegitimate love-child of King Charles III and Queen Camilla.

He was born on April 5, 1966, in Portsmouth, in the UK, and was adopted at eight months old.

The 58-year-old claims that as a child, his adoptive grandmother – who worked for the late Queen Elizabeth II – told him on her deathbed that he was Charles and Camilla’s son.

The father-of-nine also claims that in the months leading up to his birth, Charles was sent to Australia to study, and Camilla disappeared from the public eye for about nine months.

With the King and Queen due to touch down in Australia on Friday, Mr Dorante-Day shared a post to Facebook last month claiming there were ‘inconsistences’ between the facial features of Charles and his sons William and Harry.

‘This comparison of William, Myself, Charles, and Harry demonstrates something very clearly, there is no consistency,’ he said, along with a photo of each of their faces beside each other.

‘The fact that the left side of my face identically matches Charles whilst neither William nor Harry’s does, raises the obvious question, just who are Charles’s real sons?

‘This is why my wife, Dr Elvianna, and I believe a four-way Paternity test is the only way to resolve this issue once and for all.

‘The truth of the game that has been played by the Monarchy, the Government, and the Establishment for 58 years needs to be exposed.’

Daily Mail Australia is not suggesting there is any truth behind his claims.