The 1st and 2nd editions of the historic 25-inch O. S. maps, published in 1875 and 1899 respectively, name Felin-fach but do not depict its purpose. The best evidence that there was a mill here is provided by the existence of a near-rectangular pond some 12 metres x 12 metres, fed by a short leat from the north and a longer one on the eat side of Nant Tirmynydd, though not abstracting from the stream of that name. The leats are only depicted on the 1900 map. The stone-built dwelling now on site may incorporate the mill building.
W J Crompton, RCAHMW, 25th April 2019.