Senghenydd is a mining community 15 km north-west of Caerphilly, and 25 km north of Cardiff, which was the scene of the worst mining disaster in British history. The Universal Steam Coal Co discovered good coal seams in the vicinity in the 1890s and proceeded to open a mine that was exceptionally deep for its time. There was an underground explosion on 24 May 1901 when 83 miners were below ground preparing for the arrival of the day shift. Only one man escaped, and the death toll would have been much higher had the explosion occurred a few hours later. A full shift was working on 14 October 1913 when a further explosion took place, killing 439 miners, which was probably caused by faulty electrical equipment igniting methane gas.
The Senghenydd mine was taken over by the Lewis Merthyr Company but coal production ceased in 1928, although it was not until 1963 that the colliery buildings were demolished, and the shafts were capped in 1979. This and similar accidents in the early 20th century contributed to the bitterness between miners and employers that characterised the South Wales Coalfield. It is extraordinary that there was no memorial to the victims of the two disasters until 1981, and that is simply a crude representation of a colliery headstock that was erected near the site of the mine. It was removed when the Nant-y-parc School was built and now stands on the access road to the school, in a less prominent place in the community than the memorial to the 63 men from Senghenydd who died in the First World War and the 21 who failed to return from the Second World War. The Senghenydd disasters feature in This Sweet and Bitter Earth, one of the novels of Alexander Cordell (1914-97), and car-based tours now featured on the Cordell Country website now incorporate visits to Senghenydd.