Sadly, it probably already is damaging the foundation. Better late than never, though, so I would remove it

We have a holly less than a metre from foundations... has been there for 35 years and seems well and, no we didn't plant!

I looked up the safe distance for holly for you and it said 6 metres. I seem to remember it can be affected by your soil type too - a heavy clay presents more of a problem than a softer loam when it dries out and shrinks. Having said that lots of trees are planted closer than that without damage - just a matter of whether you want to take the risk.

Well, I can't argue with success, MG! I knew that there were worse things to plant near the house than a holly, but one 20 feet tall would have me inspecting for cracks twice a year with any species.

Ours is around 10 foot and the house is an old, very solid stone one - all seems well. I think it's growth is confined by the stone wall at the front of the garden, it has grown over the years but not hugely.

One of the problems with removing a tree is that the removal of the roots can cause as much damage as leaving the tree in place. At the moment the tree is removing a lot of moisture from the soil and once the tree is gone, that moisture stays in the soil and can cause dampness. Then there is the problem that the soil can shrink as the roots decay causing subsidence. My parents had this problem when a huge Sycamore had to be removed from their garden. They had to have a concrete raft floated under their cottage as the soil shrank away from the foundations
Very difficult. I would leave it where it is and inspect the house walls on a regular basis and then get a really well qualified Tree surgeon or Structural Engineer to look at the problem.

You could take the halfway measure - have it cut down by half, and prune it back every couple of years or so to keep it from getting too large. Restricting the topgrowth does help to restrict root spread.

On checking again our holly tree is a good two metres away from the house.