Dulais Colliery, Onllwyn

Overview

A small anthracite colliery at Onllwyn on the northern outcrop of the coalfield, worked by the Dulais Anthracite Colliery Company from the 1900s until the 1930s. An explosion in its new pit killed three men in 1907.

History

Dulais Colliery was an anthracite slant at Onllwyn, at the head of the Dulais valley, on the Breconshire side of the old county border and on the northern outcrop of the coalfield. It was first served by the Neath and Brecon Railway. The Dulais Anthracite Colliery Company owned it throughout and never joined the Monmouthshire and South Wales Coal Owners' Association. It employed 28 men in 1903.

In 1905-06 the company sank a new pit to the Bluers seam. Early on 9 September 1907 gas fired there while a fireman and four men were at work, and three of the men died of their burns in Swansea Hospital over the next eleven days. Welsh Coal Mines describes the colliery then as a small one raising about 150 tons a day.

Employment reached 370 in 1910 and stood at 297 in 1911, under the manager A. F. Railton. By 1923 there were 193 men producing 50,000 tons a year, and in 1935 there were 207 working the Peacock, Bluers and New seams; the chairman then was Commodore C. E. Evans and the company's office was in Fenchurch Street, London. The colliery had its own washery.

The drift abandoned the New or Bluers seam in 1917 and the Nine-Feet in 1926, and the East Slant gave up the Peacock seam in 1927 and was itself abandoned in 1928. The colliery closed before nationalisation in 1947.

Geology

Anthracite of the northern outcrop of the South Wales Coalfield. The colliery worked the Peacock, Bluers (New) and Nine-Feet seams; the mine plans also name the Rhyd, Grey, Rider and Gnapiog.

Workings

A slant or drift, an East Slant, and a pit sunk in 1905-06 to the Bluers seam, worked with naked lights in 1907. The colliery had its own washery.

Closure

The drift abandoned the Bluers seam in November 1917 and the Nine-Feet in February 1926; the East Slant abandoned the Peacock in November 1927 and was given up in 1928. The colliery had closed by 1947. The reason is unknown.

What remains

Unknown.

Redevelopment

Unknown.

Disasters & major incidents

• Dulais Colliery explosion, 1907
  9 September 1907 · Explosion · 3 fatalities
  Gas fired in the new pit at Dulais Colliery, Onllwyn, before dawn on 9 September 1907, burning four men; three died in Swansea Hospital over the following eleven days.

Recorded claims

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

• The Dulais Anthracite Colliery Company owned the colliery throughout its life and did not join the Monmouthshire and South Wales Coal Owners' Association. ¹
• A new pit was sunk to the Bluers seam in 1905-06. ¹
• An explosion in the new pit on 9 September 1907 killed three men. ^2,1,3
• In 1907 it was a small colliery raising about 150 tons a day. ²
• The colliery employed 297 men in 1911 and 207 in 1935. ¹
• The East Slant abandoned the Peacock seam in November 1927 and was itself abandoned in 1928. ¹
• The Dulais Anthracite plans record the Peacock, Rhyd, Grey, Rider, Gnapiog, Bluers, Nine Feet and New seams. ⁴

Photographs & further reading

Sources

1. (secondary) Dulais Colliery — Northern Mine Research Society
2. (secondary) Mining fatalities, 1907 - Welsh Coal Mines — Welsh Coal Mines
3. (primary) Third death from the Onllwyn explosion (Evening Express, 21 September 1907) — Welsh Newspapers (National Library of Wales)
4. (primary) DULAIS ANTHRACITE: mine plan catalogue entry (Peacock, Rhyd, Grey, Rider, Gnapiog, Bluers, Nine Feet, New seams) — British Geological Survey / Mining Remediation Authority
5. (primary) Death of Henry Birch after the Dulais Pit explosion, Onllwyn (Evening Express, 11-12 September 1907) — Welsh Newspapers (National Library of Wales)
6. (primary) Explosion at Onllwyn (Baner ac Amserau Cymru, 11 September 1907) — Welsh Newspapers (National Library of Wales)

Record created: 8 October 2026 · Last researched: 8 October 2026