Turns out that the house next door is listed. Not because of it's box-on-stilts appendage on the front that partially blocks our view of Portstewart Strand. Nor for its once-pristine white walls or vantage point overlooking the sea, beach and Castlerock in the distance.
No. Because it has a mosaic on its front wall that was designed by Colin Middleton.
I'll post a photo and an explanation when I get back (assuming the weather clears up to allow me to stand outside long enough to take a picture), but there's a special prize (*) for anyone who can post a comment explaining the signifance or merit of a Colin Middleton mosaic on the outside of an otherwise derelict building (without resorting to wikipedia).
There must be some Ormeau Baths Gallery aficionados reading (maybe Jett Loe) who know their Irish art/artists ...
(*) special = no prize, just the recognition of being right!