New research has laid bare the full extent of the King's vast property empire in Norfolk, covering around 300 homes in at least 13 villages.
The study has been conducted by the Guardian and involved an analysis of Land Registry documents relating to properties in the north west of the county.
The newspaper estimates the total cost of the King's portfolio at around £75m, in addition to his own Norfolk home, Sandringham House, which is said to be worth around £100m.
As well as the homes, the research also found the monarch personally owns the freehold of at least 37 commercial properties in the Sandringham area.
They include shops, a post office, social clubs, a medical centre, a church, a primary school and a nursery.
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All were inherited after the death of his mother, Queen Elizabeth II, last September.
Many of the homes owned by the King were formerly estate workers' cottages in villages such as Flitcham, Wolferton and Anmer.
In Flitcham alone, there are at least 39 properties owned by the King.
In Anmer, every house is owned by the Windsors. The queen’s purchase of the old school house in 2006 for £625,000 completed her ownership of the entire village.
Its most famous residents are the Prince and Princess of Wales, who live part-time in Anmer Hall, a 10-bedroom manor with a heated outdoor swimming pool and a tennis court.
Queen Elizabeth gave the house, which dates back to 1802, to the couple as a wedding present.
Many of the King's properties are built from brick and carrstone, with light blue front doors - a colour chosen by the late Queen Mother.
Several have royal-themed names, such as Diamond Jubilee, Victoria or Queen’s cottages.
Many are rented out to tenants for around £750 - £950 a month, who agree conditions including the estate's ban on keeping cats in case they kill game bird chicks. Caravans are allowed on site for only six weeks at a time.
In the 1980s, the royal family sold off some properties.
Those who now privately in the area often have unusual covenants attached to their freehold, such as restrictions on putting up fences in case they interfere with game birds.
In recent years, however, the royals have started to buy back properties, including in Dersingham and Wolferton.
Sandringham's policy is to let to those who live and work locally, who will use the property as their main home.
Others are used as holiday lets offered out for more than £1,000 a week.
The Guardian estimates the King's rental income from the estate at £4.5m a year.
There are also eight tenant farms, totalling 10,000 acres, on land worth a further £100m.
The King took over the management of the estate in 2019, after his late father Prince Philip retired from public life.
Since then he has converted it to organic methods of farming and planted trees and hedgerows.
Taking into account the many rental properties, the farmland, commercial rentals and the grand mansions, the Guardian calculates Charles has inherited an estate worth between £250m and £390m.
STARTER HOME SANDRINGHAM
The Royal's first foray into the Norfolk property market came in 1862, when Queen Victoria bought Sandringham House for the then Prince of Wales, later King Edward VII.
When Queen Elizabeth inherited it from her father, George VI, it was said to be haemorrhaging money.
Prince Philip is credited with stepping in, reducing staff numbers, knocking down parts of the building and, in 1977, opening up sections of the house to the paying public.
A ticket to visit the house and gardens costs £23.
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