Cwm Colliery

Overview

Sunk from 1909 by the Great Western Colliery Company, which had been incorporated to raise steam coal for the Great Western Railway, and the making of Beddau as a village. Its two shafts were named the Margaret and the Mildred after two ladies present at the cutting of the first turf, and were given the largest pit bottoms in the South Wales coalfield. Powell Duffryn took it over in 1928. A £9 million reconstruction in the 1950s linked it underground to Coedely, creating the largest colliery in the coalfield, and a coke works opened alongside in 1957-58 to centralise South Wales foundry coke. The pit closed on 28 November 1986; the coke works ran until June 2002.

History

The sinking of Cwm Colliery in 1909 by the Great Western Colliery Company Ltd began Beddau’s rapid growth. The company had been incorporated to sink pits around Pontypridd to supply steam coal to the Great Western Railway. The wife of the managing director, Mrs C. H. James, cut the first turf; among the local dignitaries present were Lady Margaret and Lady Mildred Bramwell of Tir Mab Ellis, and the two shafts sunk were known ever after as the Margaret, the upcast, and the Mildred, the downcast, each about 750 yards deep with the largest pit bottoms in the South Wales coalfield. Sinking was still going on in 1913, when 212 men were employed; that rose to 603 by 1918 and 1,043 in 1923, working the Four Feet and Upper Five Feet seams. By 1934 the pit was in full production with 780 men underground and 100 on the surface, and 1,269 were employed in 1938. Powell Duffryn acquired the colliery in 1928 and held it until nationalisation in 1947, when the workforce was 1,154. An underground railway linking the Maritime Colliery at Pontypridd with Cwm was completed in 1931. A £9 million reconstruction between 1952 and 1960 included, in 1957, a similar underground link to Coedely Colliery over five kilometres west; the merger of the two created the largest colliery in the South Wales coalfield. In 1960 Cwm employed 1,470 men and produced 324,794 tons, and by the 1970s the joint operation raised 515,000 tons of steam coal a year from the Six Feet and Yard seams with 1,580 men.

Geology

The South Wales coalfield north-west of Pontypridd, worked for steam coal from the Four Feet, Upper Five Feet, Six Feet and Yard seams. The coal was notably low in sulphur, which made it particularly suitable for foundry coke and was the reason the coke works was sited here.

Workings

Two shafts about 750 yards deep — the Margaret, upcast, and the Mildred, downcast — with the largest pit bottoms in the South Wales coalfield; the Margaret was sunk to 2,384 feet 9 inches, and sinking was completed in 1914. Underground railways linked the colliery to the Maritime Colliery at Pontypridd from 1931 and to Coedely, over five kilometres west, from 1957. A coke works stood alongside from 1957-58.

Closure

The colliery closed on 28 November 1986, in the aftermath of the miners’ strike — though a British Coal publicity brochure of 1982 had stated that further underground development was exposing reserves of 9 million tonnes. The coke works, fed by Cwm until 1986 and by three other collieries thereafter by road and rail, continued until June 2002.

What remains

After closure the site became a well-known derelict and heavily contaminated industrial ruin, much visited by industrial explorers and recorded in urban exploration reports and drone footage. It has since been demolished and largely reclaimed, though extensive tips remain only partly landscaped between Church Village and Beddau, with new material still being exposed in drainage runnels.

The colliery and coke works structures have been demolished; extensive spoil tips remain, only partially landscaped.

Related mines

• Coedely Colliery — Joined underground and closed together: a roadway was driven between the two between 1952 and 1960 as part of a £9 million reconstruction, making the pair the largest colliery in the South Wales coalfield; through the 1970s they produced 515,000 tons a year with 1,580 men between them, and both closed on 28 November 1986.
• Maritime Colliery — Joined underground from 1932: a 1,086-yard drivage completed on 1 April that year linked the Maritime with Cwm, and much of the Maritime’s coal was raised through Cwm thereafter. Its closure in 1961 probably coincided with the £9 million Cwm-Coedely reconstruction, which worked the same Six Feet and Upper Four Feet seams.

Nearby mines

• Maritime Colliery — 4.6 km N
• Nantgarw Colliery — 5.4 km E
• Coedely Colliery — 5.5 km NW
• Great Western Colliery — 5.6 km N
• Lewis Merthyr Colliery — 6.3 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.

• Cwm Colliery was sunk from 1909 by the Great Western Colliery Company Ltd, which had been incorporated to sink pits in the Pontypridd area to provide steam coals for the Great Western Railway. Sinking was completed in 1914. ¹
• The wife of the company’s managing director, Mrs C. H. James, cut the first turf. Lady Margaret and Lady Mildred Bramwell of Tir Mab Ellis were among the dignitaries present, and the two shafts were known thereafter as the Margaret, the upcast, and the Mildred, the downcast — each about 750 yards deep, with the largest pit bottoms in the South Wales coalfield. ¹
• 212 men were employed while sinking continued in 1913, 603 by 1918 and 1,043 in 1923 working the Four Feet and Upper Five Feet seams. By 1934 there were 780 underground and 100 on the surface, and 1,269 employed in 1938; the workforce was 1,154 at nationalisation in 1947. ¹
• A £9 million reconstruction between 1952 and 1960 included an underground railway linking Cwm with Coedely Colliery, over five kilometres west, in 1957. The merger of the two created the largest colliery in the South Wales coalfield. In 1960 Cwm employed 1,470 men and produced 324,794 tons; by the 1970s the joint operation produced 515,000 tons of steam coal a year with 1,580 men. ¹
• Cwm coke works opened in 1957-58 to centralise and maintain the production of South Wales foundry coke, the coal mined at Cwm being very suitable for it because of its low sulphur content. It was fed by Cwm until 1986 and by three other collieries thereafter, closing in June 2002. ¹
• The colliery closed on 28 November 1986 following the miners’ strike, although a British Coal publicity brochure published in 1982 had stated that further underground development was exposing coal reserves of 9 million tonnes. ¹

Photographs & further reading

Sources

1. (secondary) Cwm Colliery — Dr Adrian Price
2. (observational) Cwm Coke, Beddau — report, March/August 2022 — 28DaysLater
3. (primary) Cwm Colliery and Coke Works, Beddau — Coflein, the online database of the Royal Commission on the Ancient and Historical Monuments of Wales

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