I found Snig's Foot House! Every once in a while when I'm cyberskiving I browse images of houses and cottages in forests. I hope that one day I might find something that comes close to the picture I have in my mind of the house that features in my current novel. Today I found it - so here it is:
(I've borrowed this pic from http://gothicbohemianstock.deviantart.com/ Hop over there for lots more great pics.)
In my novel, of course, the house isn't derelict (and in real life it isn't derelict any longer.) That lean-to on the side is an old timber-framed cottage and to the rear there is a granny annex. Otherwise, it's perfect. So, lots of gratitude to Gothic Bohemian for taking the photo in the first place and allowing use of her work.