Hi Slumpy,
I would say that no where is ever 100% safe, there are too many variables. Pressures for housing, agriculture, roads, natural resources. We're a heavily populated relatively small group of islands, so there is always going to pressure on the land.
Imagine what would happen if the predicted rise in sea levels occurs. A massive movement of population inland from the coast. Yorkshire, having more acres than words in the bible, would be a prime candidate for new communities. The fact that a parcel of land contains a scheduled monument will be neither here nor there.

doom and gloom
fitz