At 9:51am on October 21st, 1966, a huge spoil tip from a local coal mine slipped down the mountain and buried the village school and 18 homes leaving 116 children and 28 adults dead.
Sadly, the disaster could have been avoided. Underneath the spoil tip was a natural spring that, along with heavy rain, helped contribute to the spoil tip collapsing.
The National Coal Board (NCB), headed by Lord Robens, claimed it had been unaware of the spring despite it being marked on some maps. The NCB was subsequently blamed for the disaster. Robens never apologised.
Whilst that alone would have made Robens a hated man, on the day of the disaster he did not rush to the scene; he instead went to accept an appointment as chancellor of the University of Surrey.
Survivors of the Aberfan disaster, which killed 144 people, mainly children, have joined bereaved relatives at a private service.