St David's Colliery

Overview

For a while the deepest mine in the South Wales coalfield. Sinking began in an isolated spot between Bryn and Dafen in the late 1820s, hit water at 160 feet and did not reach the coal until 660 feet; the shaft was finished in June 1832. The dock at Llanelli and the railway to it were both built to carry its coal.

History

The first shaft was begun by the Llangennech Colliery Company in 1827 — Cadw's scheduling gives the sinking as from 1825 — in an isolated spot between Bryn and Dafen. The mine was meant to work the dry steam coal of the Swansea Four Foot seam, which was not thought to be particularly deep here. It was. Sinking was bad from the start: at 160 feet they struck a feeder of water that kept flooding the shaft, at one point running in at five hundred gallons a minute, and Cornish shaft sinkers had to be brought in to finish the job. Worse, the seam was far deeper than anyone had supposed, and was finally found at 660 feet. When the shaft was completed in June 1832 it was the deepest mine in the South Wales coalfield. On 27 June 1840 fire damp exploded underground. Twenty-six men were burned; three boys and two men were killed. By 1842 the mine employed over four hundred and twenty people. It became the centre of a spreading complex of shafts — Penprys, C pit, D pit and E pit, the last of which became Penllwyngwyn mine — connected by tramways on the surface and in places underground. That lettering of shafts is very unusual in South Wales and suggests somebody from the north of England had a hand in it. The complex needed a railway more than two miles long to take the coal to the coast, and when it turned out there was no dock at Llanelli able to handle coal in bulk, the company diverted the river Dafen and built a floating dock at Machynys. The dock has long been filled in and that part of the town is still called New Dock. The mines changed hands in 1874 and were abandoned in 1885. The Llanelli Copperworks Company bought them in 1891 and worked St David's and Penprys until 1896. The Glanmwrwg Colliery Company then worked Penprys as a separate mine, using St David's as a pumping pit, and the whole thing closed in June 1908.

Geology

The dry steam coal of the Swansea Four Foot seam, expected near the surface and found at 660 feet. A water feeder at 160 feet nearly stopped the sinking altogether.

Workings

A shaft of 660 feet, finished in June 1832 and then the deepest in the coalfield, which grew into a complex of shafts over a wide area — Penprys, and C, D and E pits, E becoming Penllwyngwyn — linked by surface and underground tramways, with a railway of over two miles to the coast and an incline worked by a steam engine down to Penprys.

Closure

Abandoned in 1885, reworked from 1891 by the Llanelli Copperworks Company until 1896, and finally closed in June 1908 after a spell as a pumping pit for Penprys.

What remains

A scheduled monument since 28 July 1994. What survives is the substantial buttressed walls of a stone pumping engine house, the heapstead, several low stone walls from ancillary buildings and engine houses, and the massive steam-powered incline house for the railway incline to Penprys. The scheduled area measures 90 m by 30 m.

The pumping engine house, the heapstead, low walls of ancillary buildings and the incline house.

Nearby mines

• Morlais Colliery — 2.2 km E
• Brynlliw Colliery — 4.0 km E, Swansea
• Berthlwyd Colliery — 5.7 km SE, Swansea
• Elba Colliery — 6.1 km SE, Swansea
• Cynheidre Colliery — 8.1 km NW

Straight-line distance, within 15 km. Show on the map.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Shaft sinking proved to be problematic; at 160 feet they hit a feeder of water which kept flooding the shaft, at one point 500 gallons per minute, and Cornish shaft sinkers had to be brought in to complete it. The intended seam was much deeper than first thought and was finally located at 660 feet. When the shaft was completed in June 1832 it was the deepest mine in the South Wales coalfield. ¹
• There was an explosion at the mine on 27 June 1840, when twenty-six men were burned and three boys and two men killed: Henry Lewis (17), William Williams (20), Thomas John (10), William Hugh (25), Griffith Morgan (14) and David Samuel (14), who died on 15 July of his injuries. ^1,2
• The complex led to a railway over two miles long to take the coal to the coast at Llanelli. There was no dock capable of handling bulk coal, so the course of the river Dafen was diverted and a floating dock built at Machynys. The dock was filled in years ago and that area of the town is still called New Dock. ¹
• The colliery was sunk by the Llangennech Coal Co. from 1825 and was the deepest mine in the South Wales coalfield. It became the nodal centre for a number of associated pits linked by horse-drawn railways, exploiting the company's construction of the Llanelli Railway in 1833 to the New Dock. The remains include the buttressed walls of a stone pumping engine house, the heapstead, several other low stone walls, and the massive steam-powered incline house for the incline to Penprys. Scheduled 28 July 1994. ³
• The mine turned into a complex of shafts over a large area, including Penprys C pit, D pit and E pit, the last becoming known as Penllwyngwyn mine. The naming of shafts C, D and E is very unusual in South Wales and there must have been some involvement with the north of England at the time. ¹

Photographs & further reading

Sources

1. (secondary) St. David's Colliery — Welsh Coal Mines
2. (secondary) St. David's Colliery — Durham Mining Museum
3. (primary) St David's Colliery, Llangennech — scheduled monument — Cadw, via ancientmonuments.uk

Record created: 11 September 2026 · Last researched: 11 September 2026