The final letter a British-born Australian sent to Queen Elizabeth II before her death has been made public by the man who claims to be the lovechild of King Charles III and Camilla.

Simon Charles Dorante-Day, 56, claims that his adoptive grandmother told him on her deathbed that he was the “secret son” of Charles and Camilla. Simon Charles Dorante-Day was adopted at the age of eight months.

The father of nine believes that this is the ideal time to let Her Majesty know what he wrote.

‘I’ve kept the contents of the letter confidential until now, but with her passing I think it’s appropriate to share my last correspondence with her,’ Mr Dorante-Day told 7News.

‘When she passed away, I was disappointed that she had died without responding to my message. That was my first thing – just sad, because that window of opportunity has closed.’

Mr. Dorante-Day spoke with Queensland’s Governor General Dr. Jeanette Young about the situation before writing the Queen in November of last year, and he mentioned this in the letter.

‘Your Majesty, firstly I hope this letter finds you well and in good spirits approaching the festival season,’ he wrote.

‘I take the liberty of approaching you via the Governor’s Office however, given the position with which my family and I find ourselves, we feel this action is justified.’

Then he says that during his childhood, medical procedures were done to change his appearance.

‘I can certainly understand, and to some degree forgive, actions that have been taken in the past in relation to my existence, but I cannot forget what has occurred,’ he wrote.

‘These actions I believe were undertaken to conceal my true identity.’

‘Furthermore, over the years of residing with the Day family, my adopted grandparents Winifred and Earnest Bowlden often spoke about the time they worked for the Royal household,’ Mr Dorante-Day continued.

‘Then on my last visit to the United Kingdom in 1998, my adopted grandmother Winifred told me herself, that my birth parents were your son Charles and his wife Camilla.’

He continued by saying that it would be “naive” to assume that the Queen was unaware of the allegations or that she hadn’t been closely monitoring the situation.

Mr. Dorante-Day requested assistance with his case in the formal letter’s closing statement.

‘Subsequently, you will all be aware of the actions I have recently commenced and the level of attention this has already received,’ he wrote.

‘I am writing on behalf of my family and I to ask for your assistance in coming forward and resolving this issue and stopping this global assault.

‘May God give you the strength to come forward.’

Mr. Dorante-Day has long expressed his desire for the royal family to submit to a DNA test to establish his genetic heritage. He has even sought senior legal counsel after another letter he wrote to the Queen outlining his situation failed to receive a respectable response.

‘It’s hard not to take Charles naming William as the Prince of Wales as anything other than a kick in the face,’ Mr Dorante-Day previously told 7News.

‘I don’t want to feel that way, but I do. I just think, the least Charles can do is give me an answer – acknowledge me. He gives William a title like that, well where’s my answer? Where’s my DNA test? If you are not my father, then prove you’re not.’

The Australian reiterated his resolve to pursue legal action in an effort to compel the King to submit to a paternity test.

‘There has been a discussion in there between a judge and myself and his barrister about the legal standing of Charles, and whether the monarch is protected by the law or is above the law,’ Mr Dorante-Day explained.

‘And the answer to that was no – they told me that we don’t see any reason why he is. And secondly, Camilla and her family are certainly not above the law. So that argument’s already been had and settled.’

Mr. Dorante-Day was born on April 5, 1966, in Portsmouth, England. He was adopted at the age of eight months, and his family later relocated to Australia.

Mr. Dorante-Day claims that his adoptive grandmother informed him that he was the son of Charles and Camilla. Both of Mr. Dorante-adoptive Day’s grandparents had worked for the Queen and Prince Philip in one of their royal households.

According to Mr. Dorante-lawsuit, Day’s King Charles and Queen consort Camilla started dating in 1965, which is a year earlier than the year listed on his birth certificate.

He asserts that King Charles was sent on a trip to Australia nine months before he was born and Queen Consort Camilla was missing from the British social scene.

He claims to have been told that it was a requirement of the adoption that his names, Simon and Charles, not be changed. Mr. Dorante-Day insists that Camilla kept him until he was eight months old, hiding him from the public with the help of the royal family and protection officers.

By eight months, he was becoming too big to conceal, so it was arranged for Mr. Dorante-adoptive Day’s grandmother, the daughter of a royal household staff member, to take care of him.

Inconsistencies in his name and birth certificate, according to Mr. Dorante-Day, are further evidence that he is descended from royalty.

However, his chronology of events conflicts with official records, which state that the new King and Camilla first met five years after the birth of Mr. Dorante-Day.

According to Mr. Dorante-research, Day’s Charles and Camilla first grew close in 1965 after getting to know each other at Winston Churchill’s funeral in January of that year.

However, it is widely believed that Charles and Camilla first connected at a polo game in Windsor Great Park in 1970.

You know, sir, my great-grandmother was the mistress of your great-great-grandfather, so how about it?, she allegedly said as she introduced herself. – a reference to Edward VII and Alice Keppel, his mistress.

Ten years after divorcing Andrew Parker Bowles in 1995, she wed Charles at last in 2005.

Following the passing of Queen Elizabeth II, Mr. Dorante-Day last week shared a tribute to his fictitious grandmother.

When he awoke on Friday, he claimed his daughter Meriam had told him that Her Majesty had passed away.

‘Like everyone on the planet it would be hard not to be affected and saddened by her passing,’ he wrote.

‘Since finding out about the loss of my grandmother aka Lilibet, I’ve been inundated with messages of condolence for the loss. Thank you all for your kind words, thoughts, and concern.’

The monarch’s passing, according to Mr. Dorante-Day, also signified the loss of his opportunity to ‘pleasantly’ learn more about his ancestry after she didn’t reply to a letter he wrote to her.

He vowed to keep working to prove beyond a shadow of a doubt that the new sovereign and his wife are his real parents.

‘As many of you have expressed my family and I are mourning not just the loss of Her Majesty but the loss of another opportunity to resolve this issue pleasantly, the right way,’ he said.

‘So, despite the lost opportunity of getting to personally hear her version of events, and the great sadness we all feel at her passing, on a personal and public scale it will be business as usual.’

Mr. Dorante-Day previously stated that he believes the Queen is now “free” to do as she pleases in the afterlife without any criticism “like she had her entire reign” and that she has been “reunited” with the late Duke of Edinburgh, who was her “greatest love” and “closest friend.”

She wouldn’t want anyone to feel sorry for her, he claimed, so instead ‘she would rather we all celebrate and remember her for what she stood for and the changes that she was able to make during her reign’.