Lock House, 146 Hillsborough Road, Lisburn, County Down, BT27 5QY

Lock House, Hillsborough Road, Lisburn

A single-storey L-plan lock keeper's house dating from the 1780s, probably designed by Richard Owen, engineer of the Lagan Canal. The house sits on the east side of the topmost lock (no. 17) of the Union Locks, a scheduled complex that formed a staircase of four successive chambers connecting the Lagan Navigation with the Lagan Canal. The building was constructed by the Company of Undertakers of the Lagan Navigation to service what was an essential function: managing the speed transfer of barges between the navigable river and canal system.

The house is a two-bay structure with a hipped natural slate roof, fitted with clay ridge tiles and a skylight to the north pitch. The walls are cement-harled masonry, probably random rubble beneath. All window and door openings have flat heads delineated in cement render, with sandstone cills throughout. The principal north-facing façade is symmetrical, with a central tongue-and-groove sheeted door (now with a boarded rectangular overlight) flanked by windows. A structural crack is visible above the doorway. The window to the left retains vestigial evidence of a 6/6 timber sliding sash internally, though now sheeted over; the window to the right is a replacement fixed light but would originally have been a matching 6/6 sash. The west gable of the front section has no openings.

The south elevation features a projecting windbreak porch with a tongue-and-groove sheeted door; old photographs indicate this porch originally had a hipped roof, though its current roof profile is indeterminate due to vegetation. To the left of the porch are vestiges of a 6/6 sash window, with a replacement 2x2 fixed window to the right. The rear section's exposed elevation contains a single tongue-and-groove door with granite doorstep at its right end. The south gable of this section has a 6/3 sash window, and the east elevation displays three regularly spaced windows: two 6/6 sashes and a replacement 3x3 fixed light (originally 6/6).

Old photographs record three chimneys—two on the front section and one on the rear—all long since removed. The eaves are boxed in lathe-and-plaster with replacement half-round steel rainwater goods. Heavy ivy growth now obscures many parts of the external walls, rendering some window openings more evident from inside than out.

The Union Locks were built in the early 1780s to bridge the Lagan Navigation (running between Belfast and Sprucefield) with the Lagan Canal (extending from Sprucefield to Lough Neagh). The locks and lock house appear in their present form on the 1833 Ordnance Survey six-inch map and all subsequent editions. Control of the Lagan waterway passed to the Lagan Navigation Company in 1843, which operated it until the mid-20th century. The Lisburn–Lough Neagh section saw its last barge in 1947 and was officially abandoned seven years later. The lock house became redundant at that point. In 1954, the Lagan Navigation Company was dissolved and its assets transferred to the Ministry of Commerce, when the house was likely sold. The navigation between Belfast and Lisburn was abandoned in 1958. At the time of the First Survey in 1970, the house had been converted to a piggery. A modern wall was subsequently constructed between the house and the locks, severing any spatial connection.

Although the building's architectural character has been diminished by later alterations and conversion to storage use, it retains its overall external form and appearance. As the lock keeper's house for this important scheduled union lock complex, it remains a significant survivor from the Lagan Canal and Ireland's 18th-century waterway network. It has group value with the neighbouring Navigation House.