The original waterwheel machinery, designed for an undershot wheel fed by a millrace diverted from the river by a weir, was stripped out entirely, not through neglect or fire, but to help finance the Boer War. The water still runs in the race today, arriving almost immediately at the wheel-pit, as it has done for two centuries, though what it now drives is a turbine installed in the 1950s.

The mill at Dannanstown was built in the 1820s by Messrs Quayle and Richard Welstead, on a site where a smaller mill had already stood. By 1835 it had been leased to a John Furlong, and the operation was subsequently worked by H. H. Smith until 1887. The 1842 Ordnance Survey six-inch map records it plainly as "Flour Mill", a sizeable concern given the building's footprint of nearly twenty metres along its longer axis and its six storeys of stone-arched window openings. It closed in 1900, and the machinery was scrapped to raise funds for the war in South Africa, a fate that was unusual even by the unsentimental standards of industrial recycling. The story did not end there. In the 1950s a local man named James Elliott built a canning factory nearby and installed a turbine in the old wheel-pit, along with a 21-kilowatt generator, to supply the factory with electricity. That factory, now a concrete shell, closed in 1965, leaving two abandoned structures where once there had been productive industry.

The ruins today present a layered picture: the older mill's north-west elevation has partially collapsed, and the whole is heavily overgrown, but the double-gable-ended south-west face and the six-bay south-east elevation still convey the scale of what was built here. The millrace continues to carry water, making the site feel less static than most industrial remains of this age.