What killed those thirty-three people was a slow accumulation of small decisions. The London and North Western Railway ran the North Wales Coast Line on the interval system: trains were dispatched at fixed time gaps, rather than reporting their progress between signal boxes. A heavy goods train was working the Llanddulas quarry sidings ahead of the express. The stationmaster, against the company's own rules, allowed shunting to continue with the Mail expected imminently. The brake van's brake had been broken by loose shunting at too high a speed. When six wagons were left standing on the gradient above Abergele, the senior brakesman did not apply the individual wagon brakes. Another wagon nudged them. They rolled. The line falls toward Abergele on a one-in-a-hundred grade, and they rolled fast.

Local farm labourers and quarry workers arrived first. They could see what was happening but they could not get near the carriages. The flames were too hot, and there was no water - the railway runs on an embankment along the shore. The workers formed a bucket chain to the sea, two hundred yards away, passing seawater up to the burning train. By the time they put the fire out, the people inside the first four carriages had been reduced to what one witness called 'charred pieces of flesh and bone.' The carriages behind the post van were uncoupled in time and saved; no one in them died. The mail clerks in the second post van escaped with some of the letters. The leading post van burned with its passengers. The dead were never properly identified - their faces and bodies were gone.

Some of the dead had to be named by what survived the fire. Lord Farnham's pocket watch chain was recognised, and so the body was returned to his family in County Cavan. His wife was identified by jewellery near her remains, valued afterwards at six thousand pounds - jewels that had been around her neck and on her fingers when the carriage burned. Among the things gathered from the wreckage and used by relatives to identify the dead were two locks from guns, a pair of scissors, the metalwork from suitcases, and a single Bible. Coins of gold and silver had melted together from the heat. The thirty-three people who died were not statistics; they were a married couple travelling home, a judge returning to his court, parents and children making the same crossing thousands of travellers had made in safety. They simply had the bad luck to be in the first four carriages on the wrong morning.

Identifying the remains was impossible for most of the dead. Bodies could not be told apart. The London and North Western Railway Company paid for the funerals. The dead were buried together in a single mass grave at St Michael's parish church at Abergele, beneath an obelisk that still stands there. Family members came from across Ireland and England to mourn at a grave that contained, in some cases, only ash. Modern QR codes placed by the HistoryPoints project now let visitors at the grave read short biographies of each victim on their phones - an effort, more than a century and a half later, to return individual names to the dead the fire took apart. The grave is one of the more affecting sites on the Welsh coast.

The Board of Trade inspector, Colonel Frederick Henry Rich, issued his report within a month. He blamed the brakesmen, but he also blamed the company. The interval system was unsafe; it should be replaced by the block telegraph, in which a train could not enter a section until the previous one had cleared. Dangerous cargoes - paraffin, gunpowder, naphtha - should not travel in ordinary goods trains with ordinary precautions. Carriage doors should not be locked from the outside, as they had been on the Mail that day, trapping people who might otherwise have jumped. After Abergele, steep gradients began to be fitted with runaway catchpoints - sidings designed to derail any vehicle rolling backward before it could collide with a following train. The brakesmen were tried for manslaughter at Ruthin assizes the following spring; the jury acquitted them in less than ten minutes. The Petroleum Act of 1879 finally regulated the carriage of flammable liquids by rail - eleven years after the train at Llanddulas burned.

The crash site lies at 53.289 north, 3.618 west, on the North Wales Coast Line about 1.75 miles east of Abergele between Llanddulas and the town. The line still runs the same route along the shore. The mass grave is in St Michael's churchyard at Abergele, a mile inland from the sea. Best viewed at 1,000 to 2,000 ft AGL flying east-west along the North Wales coast. Nearest airports: Hawarden (EGNR) twenty miles east, Caernarfon (EGCK) and RAF Valley (EGOV) to the west. The location is unremarkable from above - a strip of railway beside the shore - and that is its own kind of monument.