One of three river locks on the Tennant canal. The fine rusticated masonry indicates that it was built as part of the Neath harbour scheme. There is a large rectangular dock basin at canal level (NPRN 34545).

(Site entry from: Hughes, S.R. & Reynold, P. "A Guide to the Industrial Archaeology of the Swansea Region", Association for Industrial Archaeology: Royal Commission on Ancient and Historical Monuments of Wales; 2nd Edition, 1989)
(KAA 05/10/2004).

A site survey was carried-out in May 1977 by David Leighton, Brian Malaws & Stephen Hughes.

Interpretation & significance. The River Neath Navigation was the longest of the south Wales river navigations within the south Wales coalfield of south central and eastern Wales although the Wye navigation, the Towy Navigation and the Cleddau are probably all longer river navigations within the greater south Wales area. It therefore made sense to have a direct connection between the Neath river and the Tennant Canal and this was originally done at Red Jacket and Neath from the start. What transformed the situation and necessitated this third lock and adjacent transhipment dock basin at Skewen was the proposal to transform a mile long tidal section of the River Neath into one of the largest enclosed or 'floating' dock schemes in south Wales (See Stephen Hughes & Paul Reynolds, 'A Guide to the Industrial Archaeology of the Swansea Region' (Aberystwyth & Swansea, 2nd. ed., 1989) pp. 25 & 35). In type the scheme is similar to that when the Swansea Town Dock (later called the North Dock) was made out of a loop in the River Tawe at Swansea c.1850 and the Swansea Canal was directly connected to it via a lock with a looped canal branch built to facilitate transhipment of coal, iron etc via wharves built between the two alongside. The Neath Harbour scheme was started by an Act of Parliament in 1878. However uncertain trade prospects and the effect of a storm on the partially completed works in the river halted the scheme in 1885 but only after very substantial works had been completed. The rock-faced masonry used on the adjacent lock and dock entrance was similar to that used on the hydraulic power house for the new docks and is typical of that date ( Stephen Hughes ,16.01.2007).