While I was at breakfast, one of the TVs in the restaurant had The Haunting tuned in. I couldn't watch with any intent, but caught some glimpses of the pretty house that was used for exterior shots.

What do you know- it's in Grantham!
http://en.wikipedia.org/wiki/Harlaxton_Manor
http://www.harlaxton.ac.uk/harlaxton/visitors/index.cfm

Might be worth a look.