Merthyr Llantwit Colliery

Overview

A Tonmawr colliery opened in 1888 by John Evan Reynolds Thomas as Llantwit Merthyr, worked on the Wenallt seam by the Merthyr Llantwit Colliery Company until 1926 and briefly reopened twice before 1930.

History

Merthyr Llantwit Colliery, near Tonmawr, was opened as Llantwit Merthyr Colliery in 1888 by John Evan Reynolds Thomas, son of the Vicar of Skewen, and went into production the following year. Its name was changed to Merthyr Llantwit in 1899.

It began as a level and a shaft. In 1900, managed by Thomas Lloyd, it employed 94 men, and in 1907, under Edward Garside, 205. By 1908 it belonged to the Merthyr Llantwit Colliery Company and employed 160 underground and 18 on the surface under T. Thomas, who was still manager in 1923. In 1918 the slant employed 83 underground and 18 on the surface, and in 1923 74 and 14, producing manufacturing coal from the Wenallt seam.

The colliery closed in 1926, was briefly reopened as Blaenavon Colliery in 1928 and as Penlan Colliery in 1929, and closed finally in 1930. Its seams were later worked by Garth Colliery, Tonmawr.

Geology

South Wales Coal Measures. The colliery worked the Wenallt seam for manufacturing coal.

Workings

Originally a level and a shaft; by 1918 the coal came from the slant. Its seams were later worked by Garth Colliery, Tonmawr.

Closure

Closed in 1926, when the Wenallt workings were abandoned; reopened briefly as Blaenavon Colliery in 1928 and as Penlan Colliery in 1929, and closed for good in 1930.

What remains

Unknown.

Redevelopment

Unknown.

Related mines

• Garth Colliery, Tonmawr — Garth later worked the seams of Merthyr Llantwit Colliery.

Recorded claims

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

• Llantwit Merthyr Colliery, Tonmawr, was opened by John Evan Reynolds Thomas, son of the Vicar of Skewen, in 1888 and went into production the following year; its name was changed to Merthyr Llantwit in 1899. ¹
• It employed 94 men in 1900 under Thomas Lloyd, 205 in 1907 under Edward Garside, and 160 underground and 18 on the surface in 1908 under the Merthyr Llantwit Colliery Co. ¹
• In 1923 it employed 74 underground and 14 on the surface producing manufacturing coal from the Wenallt seam. ¹
• The Merthyr Llantwit Wenallt seam workings were abandoned in 1926. ^2,3
• Closed in 1926, it was briefly reopened as Blaenavon Colliery in 1928 and as Penlan Colliery in 1929, and closed in 1930. ¹

Photographs & further reading

Sources

1. (secondary) Whitworth Colliery, Tonmawr — Welsh Coal Mines (Glamorgan West) — Welsh Coal Mines
2. (primary) BGS mine plans: Merthyr Llantwit (Wenallt, abandoned 1926, sheet 2 of 2) — British Geological Survey / Mining Remediation Authority
3. (primary) BGS mine plans: Merthyr Llantwit (Wenallt, abandoned 1926) — British Geological Survey / Mining Remediation Authority

Record created: 1 October 2026 · Last researched: 2 October 2026