King Charles III has a huge fortune, which makes him even richer than his mother, the late Queen Elizabeth II.
The monarch's personal net is £600million - much higher than the late Queen, whose fortune was calculated at £370million last year.
Over the years, Charles saved some of the profits he received from the Duchy of Cornwall and also earned money through housing developments, a range of biscuits and beer, as well as frugal lifestyle choices linked to environmentalism.
One of his former aides said Charles carefully rebuilt his finances after his £17million divorce settlement from Diana in the 1990s.
The King's former adviser said Charles was "tucking away some money" from the Duchy - and despite not giving an exact sum, it was described as "several tens of millions".
The monarch is also known to be meticulous about switching off lights and during an interview with Vogue, he once said he hates throwing anything away - especially clothing items - if he knows he can reuse them in the future.
According to The Sunday Times Rich List, which will be published next month and will include 350 names, Charles is richer than David and Victoria Beckham, Sir Elton John and the Warburton bread-making dynasty.
The newspaper reports that between 2011 and 2022, Charles increased the Duchy of Cornwall's annual profits by 42.6 per cent to £25.4 million.
Over 30 years ago, he also launched his Duchy Originals range, selling produce from his Highgrove House estate which were initially sold through Harrods and Fortnum & Mason before being sold in Waitrose too.
Products initially included biscuits which were then followed by beer, herbal medicine and garden tools.
The monarch also built a sustainable development in Dorset before beginning a similar project in Cornwall.
In the meantime, the duchy's income went up from renting commercial properties in London, Milton Keynes and Cornwall.
Charles owns the Crown Estate, which holds £15.6 billion of royal wealth, but cannot sell assets as the institution is independent of the Royal Family.
Royal author Robert Hardman said: "A lot of people do get confused about the royal finances — wrongly thinking that [the royal family] personally own the Crown Estate and the duchies.
"In all honesty their financial arrangements really aren't as complex as [those of] many royal families and rulers in other countries, which are often far more opaque.
"Our monarchy really isn’t as wealthy as many people would believe. I certainly don’t think the King is a billionaire."
The late Queen also had a large investment portfolio, made of blue-chip stock market shares and bonds, which is estimated to be worth around £100million.
It is not clear how much exactly Charles was given by his father Prince Philip's as his will was not made public.
Queen Elizabeth's sealed will was placed in a safe in London together with over 30 wills of other senior royals who have died since 1910.
