Between 1955 and 1991, more than 1,500 of these underground facilities were located right across the UK, roughly 10 miles apart mainly in remote rural locations. They were of a standard design and constructed of 7 inch thick, steel-reinforced concrete 20 feet beneath the ground:
If you want to be a little more mobile in the apocalypse then you might want to look into making one of these! From the outside it looks like a normal tanker but on the inside is a luxury apocalyptic pad!
How to Build a Trap: 15 Best Survival Traps -- Photo 3 | Outdoor Life