Other links of interest
The
Folly Fellowship; Its charter is "to preserve, promote and protect for
the benefit of the public follies, grottoes and garden buildings." No rentals
but there is a 'for sale' section on the website.
Wolsey Lodges; upmarket B&B's in the UK and a few abroad.
(Thanks to Phil Hibberd for telling me about the Vivat Trust and Folly Fellowship.)