An estate whose profits flow to King Charles III has used assets collected from citizens who die without a will or known relatives to upgrade its commercial property portfolio, according to a new report.

The Duchy of Lancaster, a private estate of land, property and other assets, used money collected through a feudal process called bona vacantia to improve assets including townhouses, holiday lets, rural cottages, agricultural buildings, a former petrol station and barns, the Guardian reported.

The Duchy of Lancaster profits from the holdings, which go to the reigning British monarch — in this case, King Charles. Its land and assets are concentrated in the north-west of England, but it also owns significant office blocks in London.

Through bona vacantia, meaning “vacant goods,” financial assets of residents who live in the duchy are collected if they die without a will or known next of kin. About £60M has been collected in this way in the last decade.

The same process is in place in the Duchy of Cornwall, owned by the heir to the British throne, now Prince William. The UK Treasury collects assets of those who die with no will in the rest of the country.

The money collected by the duchy is supposed to go to charity, but exemptions allow it to be used to upgrade buildings if they are of historic or local interest. As a result, only a small proportion of the money has gone to charity, instead being used to benefit the king privately, the Guardian reported, citing leaked internal documents.

“The king reaffirmed that money from bona vacantia should not benefit the privy purse, but should be used primarily to support local communities, protect the sustainability and biodiversity of the land and preserve public and historic properties across the Duchy of Lancaster estates,” a spokesperson for the duchy told the Guardian. “This includes the restoration and repair of qualifying buildings in order to protect and preserve them for future generations.”

The duchy was created when Henry III gifted the baronial lands of Simon de Montfort to his son, Edmund, in 1265. Henry then bundled this up with the land of another nobleman, Robert Ferrers, earl of Derby, and some of his own land.

At the end of March, the Duchy of Lancaster had £641M of net assets under its control, delivering a net surplus — essentially profit — of £26M. The holdings include property and financial assets. Of the portfolio, 54% is commercial property, 26% is agricultural property and 8% is residential.

Its largest commercial asset is the Savoy Estate, a London block that includes The Savoy hotel, although the duchy does not own the hotel. The Savoy forms the western boundary of the block, with the Strand to the north, the Embankment to the south and Somerset House to the east.