Ponthenry Colliery

Overview

A Gwendraeth Valley anthracite drift mine whose Pumpquart seam made it one of the most dangerous pits in Britain: 37 outbursts of coal dust and methane killed ten miners between 1920 and 1928, five of them in 1924. It closed in 1936 with its reserves unworked.

History

Ponthenry Colliery was an anthracite drift mine in the Gwendraeth Valley, near Pontyates, working outcropping seams deep underground through three slants, the Gwendraeth, Stepney and Glynhir. It may have been working as early as the 1820s, and the Ponthenry Colliery Company was formed in 1865. It worked six seams, the Big Vein, Felin, Gwendraeth, Braslyd, Pumpquart and a little of the Gras, and the Pumpquart made it notorious: its outbursts, sudden inundations of fine coal dust and methane, made Ponthenry one of the most dangerous mines in Britain, with 37 recorded and ten miners killed in four of them between 1920 and 1928. The workforce rose from 192 in 1896 to over 800 at its peak in the late 1920s. Two men were killed in 1911 when a runaway tram ran into a group waiting to ride the slant (see Disasters, below). William Thomas Williams died in an outburst in February 1920 and two more in March 1923; on 3 September 1924 an outburst in the Glynhir slant killed five men (see Disasters, below). In June 1927 an outburst with 150 men below gave ten minutes' warning and all escaped, and in July 1928 another killed two and injured over twenty. The company, a member of the Monmouthshire and South Wales Coal Owners' Association and later linked with the Amalgamated Anthracite combine, still raised 200,000 tons a year in 1935, but the mine closed in 1936 with large reserves left in the ground, simply too dangerous to work.

Geology

Anthracite seams of the western South Wales coalfield: the Gwendraeth (Yard), Pumpquart, Braslyd, Gras, Big Vein and Green, with limited work in the disturbed Gras Uchaf and Big Vein; the soft Pumpquart held pockets of gas that released outbursts of fine coal dust and methane.

Geological setting: Sedimentary Beds and Seams (well documented example)

Workings

Three drifts or slants following the outcropping seams, the Gwendraeth, Stepney and Glynhir, the main slant driven down the Gwendraeth seam at 7.5 inches to the yard; a 9-foot Waddle fan from 1894 and a coal preparation plant; the Main Slant was ventilated with compressed air in 1924.

Closure

Closed in 1936 with extensive reserves left below ground because the outbursts had made it too dangerous to work; the company was then in receivership and the colliery was offered for sale by tender in April 1936.

Disasters & major incidents

• Ponthenry Colliery runaway tram, 1911
  6 June 1911 · Haulage / Transport · 2 fatalities

  A tram that broke away from a descending journey on the steep slant at Ponthenry Colliery, in the Gwendraeth Valley, in 1911 ran wild into men waiting to be drawn up, killing two and injuring several more.

  A small fall on the road at Ponthenry Colliery caused a tram to become detached from a journey descending the steep slant. It ran wild down the slant into a number of men who were waiting at the bottom to be drawn up, killing Evan Rees, a 23-year-old collier, and one other man and injuring four or five more. One account dates the accident 6 June 1911, another 6 July.

• Ponthenry Colliery outburst, 1923
  14 March 1923 · Gas / Asphyxiation · 2 fatalities

  On 14 March 1923 two colliers were killed by an outburst of coal and gas in the No. 18 East district of Ponthenry Colliery, in Carmarthenshire, a pit notorious for such outbursts.

  Thomas Evans and Edwin James Williams were killed by the outburst. Ponthenry was prone to violent outbursts of fine coal dust and methane; in all, ten men died in four separate outbursts there between 1920 and 1928.

• Ponthenry Colliery outburst, 1924
  3 September 1924 · Gas / Asphyxiation · 5 fatalities
  On the evening of 3 September 1924 a sudden outburst of fine coal and gas in 19 East, Pumpquart seam, of Ponthenry Colliery's Glynhir slant killed five men; two more were seriously gassed. Over twenty survived by lying face down, and eight rescuers were later honoured by the Carnegie Hero Trust.
• Ponthenry Colliery outburst, 1928
  10 July 1928 · Gas / Asphyxiation · 2 fatalities

  On 10 July 1928 an outburst of fine coal dust and methane at Ponthenry Colliery in the Gwendraeth Valley killed two miners, seriously injured three and injured about twenty more. It was the last of the four fatal outbursts at the pit between 1920 and 1928.

  Ponthenry was a Gwendraeth Valley anthracite mine working several drifts, and one of the most dangerous pits in Britain for outbursts, which killed ten miners in four incidents between 1920 and 1928. On 10 July 1928 another outburst killed David John Lewis and Richard John Williams and injured more than twenty.

Recorded claims

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

• The mine began with the formation of the Ponthenry Colliery Company in 1865, a drift mine working six anthracite seams, the Big Vein, Felin, Gwendraeth, Braslyd, Pumquart and a small amount of Gras; at its peak it employed over 800 men in three drifts. ¹
• Pont Henry may have been working as early as the 1820s; the Pont Henry Colliery Company Limited, of Brecon, was formed in 1865, and the mine consisted of the Glynhir, Gwendraeth and Stepney slants. ²
• The Pumpquart seam's outbursts of fine coal dust and methane made the mine one of the most dangerous in the UK; there were 37 outbursts, claiming ten lives. ^1,2
• An outburst of gas and small coal in June 1927, with 150 men below ground, gave about ten minutes' warning, and all reached safety except two or three slightly gassed. ³
• The mine was closed in 1936 with extensive reserves left below ground, having become too dangerous to work; the company offered it for sale by tender through a receiver in April 1936. ^1,2

Photographs & further reading

Sources

1. (secondary) Ponthenry Colliery — Welsh Coal Mines
2. (secondary) Pont Henry Colliery — Northern Mine Research Society
3. (primary) Ponthenry Colliery (Gas Outburst), HC Deb 30 June 1927 vol 208 cc573-4 — Hansard
4. (secondary) Ponthenry Colliery Suffocation - Llanelli - 1924 — Northern Mine Research Society
5. (secondary) Ponthenry Mining Disaster — Llanelli Community Heritage

Record created: 19 September 2026 · Last researched: 19 September 2026