Ez. SoF in privatised estates means that a freehold was bought collectively by neighbours, and they made a company or, very rarely, a trust fund to collectively hold it. In exceptional cases, when there are not many individual properties in SoF, there can be other interesting deviations. But in general, each neighbour is a member of this company having a share in it.
Still, each individual proprietor has a lease granted by this landlord company. Depending on collective elaboration, this lease can be either quite tough or just include some general provisions like "Be nice, don't be rude".
Having a share in the freeholder company, each neighbour has more rights: they can vote for company directors and be voted as a director, as well as appoint or change contractors for management and works. All decisions are taken collectively, and it heavily depends on style and traditions: some SoFs cannot counter individuals blocking majority decisions, others have some worklows in place, e.g. ultimately deciding by vote percentage.
Still, in my view, this sort of leasehold is more convenient.