"In their different ways, Durham and South Wales became regions that propelled the development of British industrial capitalism based on coal. Yet the coals, valuable as they were, were often located in very thin seams and could be difficult to extract. Miners endured a harsh regime of heavy physical labour in often perilous conditions. The men working the Garw seam in South Wales and the Victoria and Brockwell in West Durham did so with a pick and shovel while lying on their sides, often in water. The high methane content of these coals made them prone to explosion, and there was extensive loss of life through innumerable 'disasters'. One occurred at the West Stanley colliery, County Durham, in 1909, when 168 men and boys were killed. Another, even more calamitous, took the lives of 439 miners at the South Wales Universal colliery in Senghenydd four years later. Events like these, focusing attention on the need for adequate ventilation of the mines and full safety procedures, help explain the political nature of mining trade unionism and its concern with state regulation of the industry".