Astley Deep Pit was a monument to Victorian ambition and Victorian indifference. Sunk from 1846 onwards by Francis Dukinfield Palmer Astley, the mine took twelve years to reach the celebrated Lancashire Black Mine, a four-foot seam of high-quality coal that fetched ten shillings a ton at the pit's mouth, more than double the price of ordinary coals. When the mine opened in 1858, its main shaft reached 686.5 yards, 2,060 feet, making it the deepest coal mine in Britain and possibly the world. A later shaft went down to 717 yards. At that depth the temperature climbed roughly one degree Fahrenheit for every sixty feet descended, leaving the men working in oppressive heat. About 400 people worked the pit in shifts around the clock. The total cost was over £100,000, a fortune for a single mine.

The Half Moon Tunnel had a history. It had caught fire in an earlier incident, and falls of stone and earth were a regular problem. On the morning of 14 April, miners and workers were sent to repair the roof with hand tools and, reportedly, a steam engine. Then the roof gave way completely. A collapse alone would not have killed anyone; it would have meant hours of digging to free the trapped men. But this collapse released a large pocket of firedamp, the naturally occurring flammable gas that had already caused an explosion at the same pit in 1870. The men working nearby were using open-flame lamps. Davy lamps and other safety lights had existed since 1815, but miners were expected to buy their own, and most could not. The firedamp found the flame. The explosion that followed tore through further shafts, set fire to the support beams, and brought down more of the workings.

The coroner's jury did not mince words. Of the 1870 accident, they had already found that the manager "is not competent to have the sole management of such a mine as this. The persons have been killed by want of good management." Now, considering the 1874 disaster, they returned a verdict equally damning: "That the primary cause of the explosion was the blocking up of the mouthing leading to the smithy mines. That this was an act of gross ignorance or a culpable negligence. The jury consider that there is distinct evidence as to the employment of incompetent persons and placing them in authority. The jury desire to express their strong opinion that the present system of inspection is inadequate." The Mines Regulations Act of 1873 had been passed only the previous year. In 1873, mining deaths had fallen to a record low of 100. Astley Deep Pit alone added 53 to the 1874 figures. The Act, the jury said in effect, was not enough.

Dukinfield is a small town. In 1874, the loss of fifty-four working men and boys meant that nearly every street had lost someone, often more than one. The miners' union helped the families and a public memorial was raised, though its location has since been lost. The injured, 91 of them, were carried home to be nursed. Some recovered. Many never worked again. The Manchester Guardian reported on a tangled ownership dispute, with a Mr George Newton having sold his quarter share to a Mr Ashton, and noted that no charges were brought against any owner. The men, their families, the town: they carried the cost. The shareholders kept their dividends.

The mine closed in 1901, after 43 years of a promised hundred. The slag heap loomed over the site until it was bulldozed flat in the 1970s. The three shafts were filled with concrete in the 1980s. Houses now stand on what was the colliery: Ashbridge Drive, Kingsbridge Drive, and Kentwell Close. A Blue Plaque on Woodbury Crescent, placed by Tameside Council, marks the only visible memorial: "A previously burnt tunnel was temporarily being repaired when the roof collapsed and pockets of unknown gas were ignited by open flame lamps." The men's names are recorded on a website maintained by local historians at Pitt-Dixon. The youngest were barely teenagers. The oldest were grandfathers. None of them needed to die.