What remains at Knockawillin, on the eastern side of a bend in the River Allow, is a low, irregular rise in rough grazing land, roughly 30 metres north to south and 40 metres east to west, with a shallow curving channel along its northern edge now thick with rushes. Running westward from that channel, for a little over 26 metres, are the traces of what appears to have been a mill race, the artificial channel that would have diverted water from the river to drive a wheel. A recently recut stream follows the western edge of the raised area, cutting across ground that the original watercourse once occupied.

The identification of this spot as a mill site goes back to Bowman, writing in 1934, who noted it in a field then known as 'The Mills'. A mill race of this kind is a fairly standard piece of pre-industrial infrastructure: water was drawn off a river at a controlled point, directed along a constructed channel to build up sufficient flow or fall, and then released onto or under a wheel to power grinding machinery. What makes this particular site quietly interesting is the slippage in local knowledge over the intervening decades. The name that once described this low, rush-covered ground has migrated to a neighbouring field, leaving the original site without its old marker, legible now mainly through the faint topography of the raised platform and the curve of that silted channel.