I'm surprised no one has mentioned this today http://www.bbc.co.uk/news/uk-wales-24506122 My granddad was from Senghenydd and remembers this well - he was 8 or 9 years old at the time and he's talked about fire and the smoke coming from the mine and the panic that engulfed the village with clarity. My great-grandfather was a carpenter at the mine who was fortunately working topside that day. 439 men whose lives were valued at 5.5pence each. Unbelievable. "In May 1914 the mine manager, Edward Shaw, faced 17 charges while the colliery owners, the Lewis Merthyr Coal Company, faced 4 charges. Edward Shaw was convicted of 8 of the charges and fined £24 - leading a local newspaper to publish the headline 'Miners Lives at 5½p each'. The owners were convicted of the single charge of not fitting reversible ventilation fans and were fined £10 with £5.25 costs"
Conditions in the pits were horrific in those days; 400+ men dead because of the greed of the combines. It's a name burned in to the memories of valley people, along with Aberfan.
horrendous and upsetting still. there was a 'live' run of events here https://twitter.com/Senghenydd1913 earlier
Thankfully, the standard to which mine management were held had improved by the time of the Gresford disaster in 1934 - when the only man to be held responsible was found guilty of an offence relating to record keeping, and fined £150 (plus costs).
looked up the wiki entry, some very sobering information ... Senghenydd colliery disaster - Wikipedia