Castles in the UK?

Consider Sandbanks in Poole, Dorset which has, in a group, the most expensive houses in the country short of massive stately homes. It sits on a peninsula.

Alternately the smalll town/large village of Rock, in Cornwall:

” Rock is reputed to be the home of more millionaires than anywhere else in Cornwall with exclusive villas and apartments discretely hidden amongst the trees. I have often heard it said the town has an atmosphere that is not particularly welcoming to those who aren’t in the right set and don’t have the necessary pedigree and credentials…”

Not on the millionaire scale, but for a group of strange houses in an almost isolated setting, you can hardly do better than Portmeirion. But that tale’s been done, once, superbly well.