Although the biggest part of the value of a house is the land, normally we don't need to insure it. It is usual practice to survey a house before purchase. So even if we hadn't spotted that the house was on a cliff falling into the sea, or built over an old mine, the surveyor should. Consequently we ought to be able to minimise the need for expensive insurance by being selective in where we buy. Insurance companies have a pretty good database on areas with problems with ground conditions now, right down to the postcode, and that narrows it down to about 15 houses.

Claims for subsidence damage actually peaked in 1992 at £540m when a very dry summer caused ground problems. That can be exacerbated by trees growing close to a house, because they draw a lot of water. That oak tree outside the front might look nice but it could cost you money. Cut it down and plant an acorn further away.