Maesteg Deep Colliery

Overview

A drift mine at Maesteg in the Llynfi valley, opened in the 1860s as Moffatt's Slip and known also as Cwrt-y-Mwnws, whose Two-Feet-Nine seam was sold as the best house coal in South Wales. It employed 671 men at its peak in 1910, was kept for pumping by the National Coal Board, and closed in 1950.

History

The mine was opened in the late 1860s by the Llynfi ironmasters and first called Moffatt's Slip, after George Moffatt, the company's chairman; it was later known as Cwrt-y-Mwnws and finally Maesteg Deep. The main drift was driven down 677 yards at six and a half inches to the yard, and met the Two-Feet-Nine seam after 800 yards; a steam engine a hundred yards from the mouth hauled men, coal and materials up and down. The Great Western and Port Talbot railways served it.

North's Navigation Collieries took it over, in 1890 by Welsh Coal Mines' account and in 1899 by the NMRS's, and worked it with St John's as the southern part of a take that ran north to Cymmer. Employment rose from 156 in 1896 to 671 in 1910. In 1919 the company called the Two-Feet-Nine at Maesteg Deep and St John's the best house coal on the market, and it sold washed nuts to power stations and ships, foundry coke to arsenals and dockyards, and small coal to steamers.

The drift's haulage was its danger. On 14 November 1904 a rider let a journey of night-shift men down without leave and lost control; four died, and he was jailed for manslaughter. On 31 October 1914 two boys were killed by a journey on the incline (see Disasters, below). The mine closed for a time in July 1928, employed 171 in 1935, and after 1947 was kept only for pumping until it closed in 1950.

Geology

The Two-Feet-Nine seam of the South Wales Coalfield, reached by the main drift after 800 yards.

Workings

A drift, its main road driven 677 yards at a gradient of six and a half inches to the yard, with a steam haulage engine a hundred yards from the mouth; men rode in carriages on the incline.

Closure

Working had largely ended by the late 1930s; the National Coal Board kept the mine for pumping after 1947 and closed it in 1950.

What remains

Unknown.

Redevelopment

Unknown.

Related mines

• St John's Colliery — North's Navigation worked the two together as the southern part of its Llynfi take, and sold their Two-Feet-Nine as one house coal.

Disasters & major incidents

• Maesteg Deep Colliery runaway journey, 1904
  14 November 1904 · Haulage / Transport · 4 fatalities
  Four men were killed at Maesteg Deep on 14 November 1904 when a rider who had let himself into the locked engine house lost control of a journey carrying forty of the night shift down the drift.
• Maesteg Deep Colliery haulage accident, 1914
  31 October 1914 · Haulage / Transport · 2 fatalities
  Two boys walking out of Maesteg Deep on 31 October 1914 were struck and dragged by a journey on the incline.

What's uncertain

Points where sources disagree or the record could not be settled; both accounts are kept. All open questions in the archive.

• The Llynfi, Tondu and Ogmore Vale Coal and Iron Company sank the mine in the 1860s. (disputed) ²
• North's Navigation Collieries took over the running of the mine in 1890. (disputed) ¹
• North's Navigation Collieries bought the mine in 1899. (disputed) ²

Recorded claims

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

• The mine was first called Moffatt's (or Moffatt's Slip), after the company chairman George Moffatt, then Cwrt-y-Mwnws, and finally Maesteg Deep. ^1,2
• The Llynfi Coal and Iron Co. Ltd opened the drift in the late 1860s. ¹
• The Llynfi, Tondu and Ogmore Vale Coal and Iron Company sank the mine in the 1860s. (disputed) ²
• The main drift was driven 677 yards at a gradient of 6.5 inches to the yard, and met the Two-Feet-Nine seam after 800 yards. ^1,2
• North's Navigation Collieries took over the running of the mine in 1890. (disputed) ¹
• North's Navigation Collieries bought the mine in 1899. (disputed) ²
• The mine employed 156 men in 1896 and reached its peak of 671 in 1910. ^1,2
• In 1919 the Two-Feet-Nine seam at Maesteg Deep and St John's was claimed as the best house coal on the market. ^1,2
• Maesteg Deep was retained for pumping by the National Coal Board after 1947 and finally closed in 1950. ²
• A plan survives of Maesteg Deep's workings with the Coegnant pits and Air Pit in the Old Seven Feet and Two Feet Nine seams. ³

Photographs & further reading

Sources

1. (secondary) Maesteg Deep Colliery — Welsh Coal Mines
2. (secondary) Maesteg Deep Colliery, Maesteg, Llynfi Valley — Northern Mine Research Society
3. (primary) MAESTEG DEEP / COEGNANT PITS / AIR PIT, Old Seven Feet / Two Feet Nine: abandonment plan catalogue entry — British Geological Survey / Mining Remediation Authority

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