The problem is not so much big trees as concrete and tarmac. Back in the day before the car and concrete people had front gardens which were grass and or shrubs etc. When it rained the rain soakd into the ground at the point it landed and supplied water to trees, grass etc.

Nowdays with large parts of the water catchment are tarmaced or concreted over there is'nt that immediate point of water entry into the system.

Hence tree roots now radiate out in search of water and unfortunatly end up under houses.

Cutting the trees down alleviates the problem to some extent but as most houses in London are built on clay we then have expansion of wet clay in the wet season and contracting clay in the dry. This causes the clay under most older houses with shallow foundations to have subsidence and movement.

We can cut the trees down but do nothing apart from underpinning with the clay.

My rather laboured point is, if we look after our trees i.e. pollarding etc we can alleviate this problem to a large extent.