The tip slid at Aberfan on October 21, 1966. A mountain of coal waste above the Welsh village came down in a wave, and it buried the primary school and a row of houses with it. Most of the dead were children.
The tip was built badly. It sat on the slope above the village over a spring, and warnings about its stability had been raised and ignored, and after days of heavy rain the whole mass let go. It poured down as a dark slurry, moving faster than anyone could run.
The school took the worst. Classes had just begun, and the children were in their rooms when the wave hit, and the rescuers, miners and fathers from the village, dug through the spoil by hand for days. There were few survivors to bring out.
The inquiry laid the blame on the National Coal Board. The board knew the tip was unsafe and did nothing, and the report said the disaster was not an act of God but a failure of management, which made it all the harder to bear. No senior official was ever punished.
The village never forgot. A fund was set up for the families, and the donations were partly clawed back by the government, a decision that caused lasting anger. Aberfan became a lesson about the cost of neglect, written in the names of children who never came home.