If you read up about estates like chatsworth they explain how these sorts of posh family estates are structured to basically avoid losing the estate through inheritance tax.
All the big valuable stuff (land, buildings, any big antiques etc) is endowed to a trust. In theory this will be "independently managed" in reality, the family will be represented as trustees and other trustees will be mates. For the biggest famous estates, the trust will also be a charity. The family pay "market" rent to the trust to live there (often only for a few rooms they "live in").
Tax perks:
a) Income from the estate is funnelled into the trust, which as a charity pays no tax. This means all repairs, extension, acquisitions of new stuff etc can be funded from untaxed income.
By contrast any normal person has to pay for home repairs etc from post tax pay.
b) the family get to continue to essentially have most of the benefit of the house, land, art etc and hand it down for the benefit of heirs, while paying no inheritance tax.
By contrast any other family pay tax when passing down wealth.
c) the family get to only pay "rent" for the rooms they officially use, while retaining enough control to prevent anyone else moving into live in the rest. Often the bit that gets put in the trust is all the big costly bit (the dilapidated expensive to maintain old house) while the family keep other easier assets.
By contrast, I have to pay for my whole house. If I only paid for say, the upstairs, the landlord would no doubt move someone else in downstairs.
Downside: they are stuck with it. Very difficult to move etc without losing the value.
It's a clever swindle though and it's how the very highest aristocracy can maintain their huge wealth. Often they keep proper ownership of the most income generative/low cost assets, and what gets put into the trust is the bit that's too expensive to maintain unless it's in a neat tax free charity