I'm still keeping eyes open for this one, and I thought for a few seconds I'd found it - but sadly not
https://www.onthemarket.com/details/1530089/
I got quite excited when I found this while looking for WAI 12/12a, but it set me wondering. It's Castle Hill House, Rotherfield, and according to some old planning documents at Wealden Council (you can search on postcode TN6 3RR) it has changed quite a bit over the years. (I didn't look at all the documents and plans.) One of the things mentioned was a one-storey wing at the north end (the far end of what we see - if it's the same house) which was burned down some time last century. But unfortunately our house has 3 gables on the side to the right, whereas Castle Hill House has 4, and I got the impression that none of the changes had been quite as major as that.
Another thing about it is that the local railway station for Castle Hill House is Crowborough & Jarvis Brook, as in WAI 203. I even wondered if the chap in No. 19 might be one of the ones with bikes on the platform of No. 203, though I suspect not.
Anyway, just thinking out loud, really, and trying to spot connecitons, but it might inspire someone else. Or might there be a connection between No. 203 and No. 12/12a? (Probably better answer that on 12a rather than here.)
Arthur