It was Monday, 10 March 1930. The colliery belonged to Airedale Collieries Ltd., one of about a thousand miners in the pit when the explosion happened in the Old East District. Roughly 150 of those men were working the Silkstone Seam - a thick coal measure where colliers drilled shot holes from the roof at eighteen-inch intervals, and where a deputy walked the working face setting and firing the charges. Each shot used a measured amount of explosive from Paley's canister, which had started the shift holding five pounds. There was a procedure: charge the hole, fire the shot, move to the next. There was also firedamp, the colourless explosive methane that seeps from coal seams, and there was coal dust, which can amplify a small flame into something catastrophic. The procedure managed the risk. It did not eliminate it.

George Paley was killed instantly. So was Arthur Richards. Albany Taylor and William Townend, also in No. 8 stall, were badly burned. Herbert Taylor and a colleague in 101 gate had stepped back from the coal face a minute earlier to take a meal - the kind of small ordinary choice that, on that day, kept them alive. Herbert reported the explosion as enormous, and then total darkness with choking fumes, smoke and dust. Harold Collinson, nineteen, had been in No. 7 stall waiting for John Allan and his pit pony, who were overdue. A tremendous gust of wind hit him; a report; flying stones in his back. Injured himself, he helped Albany Taylor and William Townend toward the shaft. Albany Taylor was burned but walking. William Townend was carried on a stretcher. Both were taken to the Castleford, Normanton and District Hospital. Albany Taylor died that night. William Townend died the day after.

Harry Collinson was Harold's father and the pit corporal. He had been making his way toward No. 8 gate to find out why John Allan was late. Forty yards further from the explosion than his son, he was still knocked off his feet. When he got up, he could smell burning. He passed his injured son being helped out of the mine. He could have turned back. His job was to investigate, and he walked on toward the blast site. He found John Allan, whom he had trained from boyhood, killed instantly by the explosion's force and thrown against the roadside. He found the pony. He could go no further - the afterdamp, the suffocating mixture of gases that follows a mine explosion, was filling the workings - and he was forced to leave. The story of the disaster is told in those small painful units: a father walking past his son's stretcher to find a boy he had taught.

The jury at the inquest returned a verdict of accidental death - methane ignited by the firing of a shot, no negligence attaching to any individual. But the inquest also recorded two observations that read, ninety-five years later, as the closest thing it could manage to a warning. The face had not been thoroughly treated with inert dust - the standard 1930 precaution against coal-dust explosions - and samples taken the next day showed between 45.2 and 71.2 per cent combustible matter where there should have been almost none. And the three-shot dynamo Paley had been using to fire the charges did not comply with the Explosives in Coal Mines Order and should not have been in service. Six lives - five men and a pit pony - were lost in a working morning at a colliery considered ordinary by the standards of the West Yorkshire coalfield in 1930. The standards killed people. They were what the work required.