39 Ballywoolen Road, Castlerock, Coleraine, Co Londonderry, BT51 4XF

This building at Ballywoolen Road, Castlerock, originated as a corn mill constructed in the 1840s, first appearing on the 1853 Ordnance Survey map. The 1856 Valuation book records it as tenant-operated by Isaac Duggan Junior under lease from the Worshipful Company of Clothworkers, described as "all slated with a very complete set of machinery – elevators, screens, screws, sifters and good waterpower from grindstones". The mill changed operators several times: John McFadden leased it from around 1869 until 1879, after which it reverted to Sir Henry Bruce, who had acquired it from the Clothworkers in 1872. Around 1880, the corn mill was converted to flax scutching, equipped with six sets of scutching stocks and a flax breaker. Robert McCarten operated it from 1886 to 1890, succeeded by Richard Duggan until after 1929. The 1904 and 1922 Ordnance Survey maps identify it explicitly as a flax mill. The building was severely damaged by fire but substantially rebuilt in 1943 to meet increased demand for flax during the Second World War. It appears to have closed by 1950 and remained derelict until conversion to a dwelling house in the mid-1990s.

The building comprises four sections arranged anticlockwise from north-west to south-east. Section 1, at the north end, is a single-storey, single-bay structure originally serving as the flax intake room, positioned at the mill's floor level due to the sloping topography. Its original pitched cement-fibre roof on steel trusses has been replaced with natural slate, which continues over section 2. Plastic ogee gutters run the length. Rubble masonry walls are now rendered with cement, with a "1943" date marked on the north gable. The west elevation features a flat-headed roller-shutter garage door.

Section 2 originally functioned as a flax store, a two-storey-high single open space internally. During conversion to a house, a first floor was inserted. The original cement-fibre roof has been replaced with natural slate continuing from section 1, with matching plastic ogee gutters. The rubble stone walls, originally unrendered, have had their upper portion since covered with cement render. Originally containing few openings, the section now has double-glazed timber-framed windows and new doorways inserted at both levels, all fitted with new red-brick trim to their flat heads and jambs and concrete window sills. An engine room addition on the west and open store on the east have been removed.

Section 3, at the south end of the block, was originally a double-pile single-storey building with a basement cut into the slope. During house conversion, the walls were raised approximately four feet to bring their eaves level with section 2 and create a first floor. The two original roofs were combined into a single pitch, now significantly higher than originally. The original rubble stonework has been retained to basement level, with the upper part now cement-rendered. New doors and windows have been inserted with new brick trim. At the south-west corner stands an external high-breastshot waterwheel, sixteen feet in diameter and five feet wide. The metal axle, hubs and rims survive alongside the timber arms in two sets of eight. The angled wooden buckets, forty in number, and the soleplate have rotted away. A cast-iron segment spur wheel with in-facing teeth is affixed to the inner rim and drives a bull nut mounted on the end of a shaft leading into the basement.

Section 4, the original concrete-block lean-to abutting the east elevation of section 3, has been replaced with an open-sided lean-to structure.

The building lies on the left bank of the Articlave River, supplied by a long mill race which still survives. The ground between the headrace and river has been landscaped as a garden, with the land beyond the headrace used for grazing. Fields lie to the south-east and east, with a minor public road running along their north side.

The building is constructed of rubble stone and rendered concrete block beneath pitched natural slate roofing. Rainwater goods are plastic ogee. Windows are double-glazed timber-framed throughout.

The structure was delisted on 28 September 2015. While it retains industrial archaeological interest, particularly in the surviving waterwheel mechanism and flax processing machinery, the conversion to domestic use in the mid-1990s and subsequent alterations have largely obscured its Victorian and twentieth-century industrial character, and it no longer meets the criteria for listing as a building of special architectural or historic interest.