Some things you will never become inured to. A suicide bomber decides his target will be children and teenagers at a pop concert. When children are attacked, as they were in Dunblane, as they were at Sandy Hook, as they were at Ariana Grande’s show in Manchester on Monday night, it is so detestable it will always remain raw. I wonder how many, like me, switched off the radio within seconds because the suicide bombing and its aftermath were so upsetting.

As with other recent attacks, the evidence pointed to its being a lone-wolf act of terrorism. The UK raised its terror-threat level from severe to critical. The prime minister, Theresa May, warned that another attack was possible. The bomber, 22-year-old Salman Abedi, was claimed by Islamic State. There is no logical answer to the question of why he chose to punish people who were to blame for nothing bad in the world.

The political lessons to be drawn from the bombing are small and fitful. The world is complicated, and terrorists will continue to find new means and new targets and to generate new levels of outrage. The State probably needs to review Ireland’s preparedness for such an attack. It’s hard to argue that the threat here remains low, given how unpredictable terrorist attacks have become.

Simon Carswell, who attended last night's vigil in Manchester, has written a touching piece.