Thanks very much Mabel and all. I now feel pretty confident that Jerusalem House was indeed connected with my Rhymney Baptist minister great grandfather, Taliesin, making it entirely sensible that his youngest son, my grandfather, was born there in 1877.
It also seems feasible that after the bankruptcy of its innkeeper, the Cyclops was turned into a private dwelling towards the end of the century. That also fits well with facts I do know. Quite possibly the Taliesin's eldest son, a local iron & steel works manager, lived there briefly and that was why his father died there (with him in attendance).
If anyone turns up anything else of interest that would sill be welcome too of course.
best wishes