Let's start with the injuries.
If you haven't been caught in an explosion or you don't know anyone who has, it's easy to ignore what many suffer from physical and mental wounds. People horrified by the 1998 Omagh bombing, for instance, may remember that 29 people died (one a mother of unborn twins), but few will have taken in that around 300 people had injuries and countless numbers were affected by post-traumatic stress disorder.
People lost limbs, were blinded, were mutilated, disfigured, and many more were condemned to long periods of flashbacks, nightmares and upsetting recollections of terrible scenes. The bereaved suffered appalling psychological damage that included rage, alcoholism, panic attacks, obsessional behaviour and suicidal urges.
The victims of Parsons Green were mostly bloodied, scorched or suffered crush injuries from the terrified scrum of passengers fleeing a train that they feared might blow up. They will know from media reports that they got off lightly. The bomb - which was made from an explosive known as Mother of Satan and had been filled with nails - had been incompetently assembled and only partially exploded.
London is used to bombings. Recollections of the Blitz of 1940 and 1941, when more than 30,000 people were killed and countless numbers injured by the Luftwaffe, abound. Before and after that, until comparatively recently, it was Irish republicans who dominated domestic security concerns. The bombs that Fenians set off in 1867 and the early 1880s included one in the chamber of the House of Commons. London had dozens of bombs during the IRA campaign of 1939 and 1940.
The Provisional IRA's many attacks on London between 1973 and 1996 caused 47 deaths and a vast number of injuries. Particularly lethal and notorious were the Balcombe Street gang, who between 1974 and 1975 roamed around London shooting and blowing up people in shops, hotels, pubs and restaurants, the 1984 bomb attacks in two royal parks, the 1991 mortar attack on Downing Street and the massive bombs in the City in 1992 and 1993 and in Docklands in 1996 before the IRA mostly gave up murder.
Londoners didn't have long to savour a city without bomb scares, since those who had acted on the evil ideology of physical-force Irish nationalism were soon replaced by adherents of Islamism. While the Provisional IRA were happy to kill for Ireland they weren't too keen on dying for it, unlike the Muslim suicide bombers who killed 52 people and injured hundreds on a bus and on tube trains in 2005.
Since then, among later atrocities we've had five innocents murdered on Westminster Bridge and eight on London Bridge. So, wearily, Londoners have once again become accustomed to threats and scares and the inconvenience that terrorism always brings with it.
Flights have ceased to be something to look forward to, and airport security is frequently preposterous box-ticking. But bureaucrats have to be seen to be doing something. They get into frightful trouble if they are seen to indulge in racial or religious profiling and so they make an example of people who pose no threat in order to give them cover for scrutinising those they believe do. I've lost track of the number of times in American airports that I've been singled out for special attention along with a dusky young man with a big beard and a nervous demeanour.
As someone who has always been suspicious of any moves to erode civil liberties, I'm depressed to find myself increasingly relaxed about the prevalence of CCTV in the UK and I am now actively in favour of identity cards, which I used to argue against vehemently. When you've got an enemy that thinks you deserve to be murdered if you don't worship Allah or are in the wrong Islamic sect, security takes precedence.
Whatever the Taoiseach decides to do about tightening up national security, it's time Irish people faced the fact that there are jihadis in their midst. Islamists don't care about niceties like Irish neutrality: they want to subdue or wipe out infidels. The Irish Council for Civil Liberties is understandably steamed up about the possibility of mandatory national identification cards, but there are worse threats than that, and being slaughtered on public transport is one of them.