I also don't think it quite gives the right impression to say "[t]ypically this land belongs to wealthy families, old institutions, the Church, or the Crown". I

I also don't think it quite gives the right impression to say "[t]ypically this land belongs to wealthy families, old institutions, the Church, or the Crown". I zoomed in on my house, and the three largest parcels of unregistered land nearby were a public park, a school (a Church school, but I don't think that's quite what people imagine when they hear 'land owned by the Church'), and one has a fire station on it.