Are you referring to Hampton Manor at Stoke Climsland? According to Google Books it is now a place of Christian prayer, teaching and witness.
It sounds like it may have been a big house, it is described as Victorian.
The postcode for it is PL17 8LX
Is there any other kind of connection other than that your grandfather lived there?
I see that Stoke Climsland is part of the Launceston registration district.