The Prince of Wales saw his personal earnings jump last year to nearly £10m - on top of the £3m he received from the taxpayer.
Accounts from his private estate, the Duchy of Cornwall, show that Prince Charles received £9.9m in the latest financial year compared with £7.8m in the previous 12 months. During the same period, he received state subsidies amounting to about £3m.
The substantial increase in the Prince's revenue prompted urgent calls for a review into the way in which members of the Royal Family are able to receive public subsidies alongside their often considerable private income.
"We do need to examine the whole question of the Royals' funding and how, in particular, Charles is being funded," said Ian Davidson, the Labour MP for Glasgow Pollok.
"He is already receiving what seems to be an enormous amount of money to refurbish Clarence House and now we hear that his private income has rocketed to a sum that my constituency members can only dream of.
"This proves that the public accounts committee must revisit the whole question of public subsidies of the Royals."
While part of the increase in Prince Charles's personal income came from changes to accounting practices in the Duchy, more than half of the rise was the result of shrewd financial decisions taken the previous year.
In the middle of falling stock markets around the world, the Duchy sold most of its shares and invested in other financial products, such as bonds. The investment strategy paid off spectacularly, boosting the Duchy's profits from investments by £1.1m.
But despite his soaring income, he still receives large subsidies from the state.
Parliament pays grants to the Queen to cover the cost of maintaining palaces, royal travel and media relations. Prince Charles benefited from 13 per cent of the Queen's £16.6m property grant, or £2.2m last year.
While some of that money went on routine infrastructure costs such as telephone lines for his offices at St James's Palace, most was spent on refurbishing Clarence House, the former home of the Queen Mother, soon to become Prince Charles's official London residence.
Almost £2m of grant aid went on the Clarence House refit but he is also paying for some of the redecoration work himself - including accommodation for his partner, Camilla Parker Bowles.
The figures also showed that the Prince's travel by air and on the recently reprieved royal train cost £478,000 of grant money.
The profits from the Duchy, which dates back to 1337, are intended to provide a personal income for the heir to the throne. His advisers said the Prince spent £5.6m of his private income on official duties and charity activities.
The new figures are contained in a detailed breakdown of spending published by St James's Palace today in a move intended to increase transparency - giving details of the cost of everything from utility bills to office stationery.
The figures do not show exactly how much the Prince is left with for his personal use but they do reveal that tax and personal expenditure combined amounted to £4.2m.
Although he pays tax at 40 per cent, much of the spending on official duties can be treated as business expenditure for tax purposes, making it difficult to estimate how much he is left with for his use.
As well as 91 official full-time employees, Prince Charles has a private staff of 17, including a chef, valets, gardeners and grooms whose salaries are paid out of his pocket. His other main indulgences appear to include his garden at Highgrove House in Gloucestershire, his private residence, and playing polo, which his aides say he does for charity.Reuse content