Most of the post-medieval corn mill at Ballycloghduff has been levelled, the mill race largely filled in and covered with concrete, yet the stonework that survives tells a story that reaches back well before the mill itself was built.

The connection between milling and the Dillon family here runs deep. In 1612, Robert Dillon of Cannorstown was granted, by royal patent, a castle, a bawn (an enclosed defensive courtyard typical of Plantation-era fortified houses), thirty houses, and a water-mill in the townland then recorded as Bealanecloghduffe and Killnedrae. The 1659 Down Survey map of Drumrany parish, a mid-seventeenth-century mapping project that documented landownership across Ireland before and after the Cromwellian upheaval, shows the watermill as a building with a waterwheel standing on the western bank of the Tang River, or on a mill race diverted from it, right beside the castle. The accompanying terrier, a written description paired with the map, notes that in 1641 the castle and lands of Ballinacloghduffe and Ruans belonged to Henry Dillon and John Dillon, described in the document's blunt language as "Irish papists." It is possible, though not certain, that the later corn mill was built directly on the footprint of that earlier medieval watermill.

What remains today is fragmentary but quietly compelling. A small section of the eastern end of the mill building survives, and a preserved stretch of mill race at the western end of the farmyard contains the reused castle spandrel set into its stonework. Along the river, near the weir, cut stone fragments from Ballycloghduff Castle have been pressed into service as facing stones for the eastern bank, a practical recycling of dressed medieval masonry that was common as castles fell out of use and their cut stone became a convenient local building supply. The castle site itself lies about 45 metres to the north-west, in the same slight hollow.