Elizabeth II
In 1966, the Aberfan disaster, which was a collapse of a colliery spoil tip onto the village of Aberfan in Glamorgan, Wales. It killed 144 people, most of whom were children. She decided not to visit the village in the aftermath because she thought her presence would take attention away from finding survivor. It was argued that her visit would calm the chaos. Elizabeth visited 8 days later. It is said that not going to Aberfan straight away is her biggest regret.