KING Charles and Queen Elizabeth took more than £1 billion in income from two controversial property empires, it has been revealed.

A Guardian investigation unearthed the scale of the income the monarch and his late mother received from the duchies of Lancaster and Cornwall, which run huge portfolios of real estate in England.

The two professionally-run estates have been at the centre of a centuries-long debate over whether their profits should go to the public instead.

Duchy accounts, held in parliamentary and state archives, have revealed how the late Queen and Charles – in his role as the Duke of Cornwall -  benefitted from a huge increase in their revenues from the duchies during Elizabeth's reign.

Last year, their duchy income totalled £41.8m. Factoring in inflation, it means the pair have received the equivalent of more than £1.2bn in total revenues from the two estates.

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The duchies operate as professionally-run real estate empires that manage farmland, medieval castles, hotels, offices, shops and some of London’s prime luxury real estate.

Profits from the Duchy of Lancaster – valued at £652m - pass automatically to whoever is on the throne.

The Duchy of Cornwall is worth more than £1bn and its profits automatically go to the male heir to the throne. The profits from the estate now go to Prince William, making him a billionaire and one of the largest landowners in England.

The royal family’s claim to the profits goes back to when England was divided into medieval fiefdoms.

Generations of MPs have since called for the duchy profits to go to the Treasury instead, with each debate usually coinciding with a new monarch.

The royals insist their duchy income is “private” and the government treats it as entirely separate from the sovereign grant - the annual payment the royal family receives from the government to cover its official costs which costs the taxpayer £86m a year.

Buckingham Palace did not comment on The Guardian’s figures.

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The family have never revealed exactly how the cash is spent, despite having suggested it is used for official duties, public work or charitable causes.

Charles has reported 49% to 51% of his duchy income was spent covering public and charitable functions in recent years.

As Prince of Wales, a large part of Charles’s duchy income was spent privately, including on secretaries, valets, gardeners, chefs, stable hands and farm workers.

Queen Elizabeth was reported to have used Duchy of Lancaster income to help Prince Andrew pay an undisclosed sum of what is thought to have been more than £9m to end the sexual assault case filed against him by Virginia Giuffre.

What are the duchies?

The Duchy of Lancaster dates back to 1265 when Henry III seized land after a failed revolt by feudal lords  who wanted to limit the powers of the king and gain some representation. The king gave the land, mostly in the north, to his son Edmund.

In the 14th and 15th centuries, two other kings – Henry IV and Henry VII – issued charters reasserting their claim that the Duchy of Lancaster would always remain in the private hands of whoever was on the throne.

The Duchy of Cornwall was created in 1337 by King Edward III to provide an income for his son from land in southern England. He stipulated via royal charter that the estate would always be owned by the male heir to the throne.