Felin Arw lay to the north of Llangeinor on the east side of the Afon Garw, in Cwm Felin Arw, a tributary of the Afon Garw and close to their confluence.
On the Tithe map (c.1840) it is recorded as a corn mill fed by a leat which tapped the Garw from the north at SS 91278830, a distance of 0.75 km. By the time of the OS first edition map (1876) the leat had been cut through by the GWR Cwm Garw railway. It still functioned as a corn mill, the water source seemingly replaced by the stream through Cwm Felin Arw. The line of the original leat was still shown on the map (as a boundary) aside from the first 40m which was now enveloped in woodland. The mill had gone out of use by the time of the second edition map (c.1900). The site has been redeveloped and traces of the mill largely destroyed though the course of the original leat appears to have survived, in part.
This is believed to be one of five mills recorded in fourteenth century manorial accounts for the Ogmore lordship (later part of the Duchy of Lancaster Estate), three of which lay in the Welshry; one of these was the 'mill of Garw' (1). Although an early nineteenth century estate map implies the mill is a post-1637 tenement (in a list given on the map) (2), a survey of 1616 (part of a plea roll of James I) gives Felin Arw as a water grist mill with suit of mill obligations and therefore a medieval foundation (3)
The mill allegedly had a recent history as a woollen mill (4); however, the map evidence does not support this.

(1) NA, DL 29/592/9444 Lordship of Ogmore ministers' accounts 36-37 Edw III (1363-4)
(2) NLW, Dunraven Estate Map. Plan of the parish of Llanginor in the lordship of Ogmore. By David Lewis, 1820.
(3) NLW, Dunraven Estate Papers. Ogmore manor or lordship, Llangeinor parish. 4/1 (Box 4). Typescript copy.
(4) C.T.Davies, 'An historical account of Felin Arw, Tynyrheol, Llangeinor,' Melin 20 (2004), 3-12.

David Leighton, RCAHMW, 13 July 2011