Diamond Colliery

Near Ystradgynlais, Swansea Valley

An anthracite slant that was situated on the northern outcrop just inside the old Breconshire border. It was opened by the Diamond Anthracite Mine Company, and by 1913 in the possession of the New Diamond Colliery Company of Queen’s Buildings, Swansea. The manager was D.W. Davies. The sales agent for this Company, which was a member of the Monmouthshire and South Wales Coal Owners Association, was T. H. Henderson who went on to form Henderson’s Welsh Anthracite Collieries Limited, which ultimately became a subsidiary of Amalgamated Anthracite Collieries Limited.

By 1921 the colliery was owned by Diamond Anthracite Collieries Limited, and by 1932 it was under the Amalgamated Anthracite Collieries banner. Diamond Anthracite Colliery was served by the London, Midland and Scottish Railway’s, Midland and Swansea Vale Section, In 1908 it employed 185 men underground and 42 men on the surface with the manager being T.R. Davies, in 1916 it employed 450 men under the same manager while in 1918 the manager was W. Howells and the mine employed 230 men underground and 49 men on the surface. Mr. Howell was still the manager in 1919 when it employed 310 men.

In 1925 it was owned by the Gurnos Anthracite Collieries Limited and in 1930 it was part of the Amalgamated Anthracite Collieries Limited at that time this colliery employed 400 men with the manager being J.S. Evans. In 1935 it employed 400 men when managed by J.S. Evans. The No.1 abandoned the Upper Black, Brass, Nine-Feet and Big Veins in 1935, while the No.2 abandoned the Cornish and Three-Feet seams in the same year. In 1945 W.O. Jones was the manager but only 6 men underground and 2 men on the surface were retained for pumping purposes.

Amongst others, it worked the Bute (Brass) seam at a thickness of 39 inches. It was working the Four-Feet seam when closed by the National Coal Board in April 1947. Its last manager was W.O. Jones.

Some statistics:

• 1903: Manpower: 109.
• 1907: Manpower: 156.
• 1908: Manpower: 227.
• 1909: Manpower: 247.
• 1911: Manpower: 295.
• 1912: Manpower: 116.
• 1916: Manpower: 450.
• 1918: Manpower: 279.
• 1919: Manpower: 310.
• 1920: Manpower: 350.
• 1923: Manpower: 395.
• 1924: Manpower: 389.
• 1925: Manpower: 400.
• 1926: Manpower: 393.
• 1927: Manpower: 414.
• 1928: Manpower: 401.
• 1929: Manpower: 365.
• 1930: Manpower: 400.
• 1932: Manpower: 360.
• 1933: Manpower: 526 with Gurnos.
• 1935: Manpower: 400.

Information supplied by Ray Lawrence and used here with his permission.