This is all tax-payer subsidized.

The Royal family is the largest private landowner in the UK. They have made many land purchases over decades. Marsh Farm, where he is moving, is part of a private estate owned by King Charles (Marsh Farm normally houses a caretaker farmer that took care of the farm land portion of the estate but he died several years ago and it's been empty since).
Places like Buckingham Palace and some of the other larger estates are "owned" by the royal family but the government are it's caretakers.
Estates like he is moving onto are part of the vast private holdings of the royal family.

inherited wealth passed down for a millennia from the days of kings/queens as absolute rulers. This is really no different that textile/tobacco fortunes created by the slave trade in the South.

It's absolutely disgusting. Even more so when you realize that the current royal family are not even direct lineage to the British royal family which the last direct heir died in the 1800s and the current family is a very distant branch of the family from Germany. I think the guy that took over was the last Queen's 2nd or 3rd cousin who ruled Hanover in Germany.
There was a surviving, more direct member of the family at the time but he apparently was a bit of an idiot and an asshole and a Catholic so Queen Mary opted for the more distant branch of relatives that were less controversial at the time and also protestant.

for the rest of his life.

Disgustingly appropriate

Make his ass stay somewhere at his own expense. Let Fergie put him up until his house is done. That would be a great sitcom.

he can always live in a windowless panel van with the words "Free Candy!" painted on the sides.

Thank you, Melania for the name, (Which, true to yourself, you stole from some fashion merchandiser).