In the midst of panicky calls and texts to check on family and friends in London last Thursday, there can have been few in Northern Ireland oblivious to the turnaround: people in Belfast asking people in London if they were safe, where once the calls were all the other way. The sight of real terror so close - and London is very close for everybody on this island - is a reminder of how far the slow process of peace has come, writes Fionnuala O Connor
As befits a cosmopolitan city of such size, Londoners have displayed all kinds of reactions, from vandalism of mosques through an almost fatalistic calm to those who point out that in Iraq at the moment, terror on as great a scale as that of July 7th is an almost daily experience.
People in England and Scotland who look even vaguely Asian say they fear an increase in prejudice, in random revenge attacks. The attacks have begun. As Jonathan Freedland wrote , the implications behind the realisation that these were apparently British-born suicide bombers are only beginning to sink in. Most will be trying to hold off the thought that July 7th may not have been a one-off but the first in an agonising - because unpreventable - series, as in Israel, Russia and elsewhere.
The least meaningful comment in London has been that the security services will now "want to study" how Israel deals with suicide bombers. Even the most sympathetic interpretation of Israeli policy would hardly claim that it "deals" effectively with the phenomenon of suicide bombers. Many ordinary Israelis admit they struggle to cope with the awareness that the shopper in front of them or a fellow bus passenger may at any moment explode, taking their immediate neighbours with them to eternity.
There is no deterring a bomber willing, indeed eager, to die.
Northern terror - and its ramifications elsewhere - has been bad enough without that extra nightmare dimension. Anybody who ever tried arguing republicans out of the conviction that they had a moral right to use violence will remember how useless it was to rage and plead, how immovable they were. Despite sometimes quite remarkable levels of fanaticism, neither they - nor loyalists - produced anyone remotely resembling a suicide bomber.
It seems almost indecent to mention London, let alone Iraq, Israel, Russia, in the same breath as the present day North. The shadows over the sunshine of recent days - loyalist feuding and disorder around the Twelfth - make the point.
In the early hours of the 11th, that's Monday of this week, loyalist gunmen broke into a house in north Belfast and killed 20-year-old Craig McCausland. Beyond his own family and the UVF/LVF/UDA tangle of internecine loathing, this death, horrible as it was, made little impact - perhaps the most dreadful observation that can be made when somebody has died in such a way. But there is general recognition that loyalist feuding is a leftover from the Troubles, not a new or a developing phenomenon, a blight on already bleak districts, capable of causing misery for considerable time to come and beyond easy solution.
There are some resemblances with the rioting at Ardoyne. As in June, the youth of the nationalist rioters on Tuesday night in Ardoyne, the inability of senior republicans to pacify them, the blast bombs thrown by dissident republicans and the sheer hatred on show shocked onlookers. That hatred will not dissolve for years, if ever.
The despair in Ardoyne that produces awful suicide figures will take years and close co-ordination between local people and official agencies to tackle.
But generations of young rioters have grown up through much worse times in Ardoyne, and many are now mature and useful citizens. By Wednesday morning the road past Ardoyne shops was swept and clean. Where once burned cars and the litter of rioting would have predicted the next night's repeat performance, there was instead the sense of normal life resuming. The policeman in charge of the Twelfth night operation credited Gerry Adams and Gerry Kelly with having tried to calm the storm.
Difficult as it can be to see it sometimes, there is a big picture.
Measuring progress by the distance from widespread disruption and wholesale violence is especially difficult because the end of conflict is a protracted business, given to slippage and long, frustrating pauses. Ardoyne on Tuesday night was not pleasant, but remember Holy Cross, Short Strand, Drumcree? This year's Drumcree Sunday was remarkable only for the sermon preached by its rector, who commended to the brethren before him the Derry Orangemen who talked their way to a comparatively peaceful march.
Maybe the most striking measure of progress was that brazen Gerry Adams message of condolence to Tony Blair and the citizens of London: a marker, from a man whose organisation bombed London repeatedly, that whatever they do or say in the near future, renewed IRA bombing is now inconceivable.