Ynys Dafydd Colliery

Overview

One of five collieries of the Governor and Company of Copper Miners' Cwm Avon Works, named after the farm it was sunk on and claimed as the first pit sunk in the area. A firedamp explosion in the Big Vein (Nine-Feet seam) killed twelve men and boys here on 24 May 1856 (see Disasters, below).

History

Ynys Dafydd — also spelled Ynisdavid — was named after the farm on which it was sunk, and was claimed to be the first pit sunk in this part of the Afan Valley. It was owned by the Governor and Company of Copper Miners in England, proprietors of the whole of the extensive Cwm Avon Works, of which it was one of five collieries; it was also known as No.43 pit and formed part of the wider Oakwood Colliery grouping. The pit was possibly deepened, or first sunk, in 1844, reaching a depth of 231 feet.

On 24 May 1856 a firedamp explosion in the Big Vein (the Nine-Feet seam) killed twelve men and boys (see Disasters, below). Ynys Dafydd was abandoned in 1872. The Monmouthshire Merlin's account of the 1856 explosion names the men who ran the pit: David Thomas, the colliery manager and agent, W. Gilbertson, manager of the Cwmavon works, and W. P. Struvé, the company's consulting engineer, who had the plan of the pit made. Six years later the pit was being worked as part of the company's Oakwood Colliery under the same Struvé, with locked safety lamps in the gassy parts and colliers fined at Neath petty sessions for smoking underground.

Geology

Worked the Big Vein, also called the Nine-Feet seam, of the South Wales Coalfield.

Workings

A single pit (No.43) reaching the Big Vein (Nine-Feet seam) at 231 feet, one of five Cwm Avon Works collieries.

Closure

Abandoned in 1872; no cause of closure is given in the sources.

Related mines

• Wern Colliery, Cwmafan — Both were coal levels of the same Cwm Avon Works, owned throughout by the Governor and Company of Copper Miners in England.

Disasters & major incidents

• Ynisdavid Colliery Explosion, Cwmavon, 1856
  24 May 1856 · Explosion · 12 fatalities
  A firedamp explosion in the Big Vein, deep in the workings, killed nine men and three boys; the colliery's own agent led the rescue and recovery, recorded in detailed inquest testimony.

Recorded claims

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

• Named after the farm it was sunk on, claimed as the first pit in the area, and possibly deepened or first sunk in 1844 to 231 feet; owned by the Governor and Company of Copper Miners in England as one of five Cwm Avon Works collieries, also known as No.43 pit and part of the Oakwood Colliery grouping. ¹
• A firedamp explosion in the Big Vein (Nine-Feet seam) on 24 May 1856 killed twelve men and boys. ^1,2
• Abandoned in 1872. ¹
• The firedamp explosion in the Big Vein at the Ynisdavid pit on Saturday 24 May 1856 killed nine men and three boys, four of them dying within hours of being brought up. ³
• In 1856 David Thomas was the colliery's manager and agent and W. Gilbertson the manager of the Cwmavon works, with W. P. Struvé as the consulting engineer whose plan of the pit was produced at the inquest. ³
• By 1862 the Ynisdavid pit was worked as part of the Oakwood Colliery of the Governor and Company of Copper Miners' Cwmavon works, with locked safety lamps in the gassy workings and colliers prosecuted for smoking. ⁴

Photographs & further reading

Sources

1. (secondary) Small Collieries in the Afan Valley and surrounding areas — Northern Mine Research Society
2. (secondary) Ynisdavid Colliery Explosion — Cwmavon — 1856 — Northern Mine Research Society
3. (primary) Cwmavon. The late dreadful colliery explosion (Monmouthshire Merlin, 7 June 1856) — Welsh Newspapers Online (National Library of Wales)
4. (primary) Neath petty sessions: smoking in pits (The Cardiff and Merthyr Guardian, 20 September 1862) — Welsh Newspapers Online (National Library of Wales)

Record created: 14 September 2026 · Last researched: 24 September 2026