Most British apartments are sold on a long lease, commonly for 100 years or so (particularly by the big estates), but sometimes for 999 years.
Generally the leaseholders will pay the freeholder a ground rent, which is typically pretty small, and in the long term the property will revert to the freeholder's ownership. As a consequence the freehold isn't worth a huge amount compared to the leased property that sits on it.
Here is an example of a one for sale. And it's precisely this sort of thing that Vincent Tchenguiz is selling.
The UK doesn't have a land tax, and property taxes are borne by the occupier,
so he's not getting mugged for that.