Just stumbled across this post. The Mill was used as a holiday let in the early 80s and there half a dozen statics down on the field byy the river. The Mill was caretaken by Janet & John Warwick who lived in Capel Y Ddol, one of the cottages up on the road opposite the mill. The owner was a Dr... whose name I can't recall.
Not much help sorry :~)
All the best