Three significant downsides for Al Qaeda from this attack.
1. The Advice and Reformation Committee, AQ's PR arm, along with all of the Muslim community in London, are going to take a serious hit, probably already are as I type this.
2. At least 80% of the international ill will over the Iraq war evaporated with this attack. None of the G8 leaders will be able to dissociate their presence with the timing of this attack. Their grey faces on TV today substantiate this.
3. The cell phones, the unexploded ordinance, the timers, the witnesses, the big ears at NSA and elsewhere, all the intel will coalese towards those nations supporting AQ leadership for this attack. (My money's on Iran)
Relations between Britain and that nation will....chill.
Or perhaps heat up.
The police here in the UK have been pretty successful so far in preventing this, they've stopped multiple attempts that w know about already, but we all knew we could expect one to get through. Now the issue is putting them out of business.
Mr Blair himself said "Not if, but when it happens" and as you probably saw, our emergency services, well used to bombings because we've had quite a lot over the years, were prepared and our citizens behaved with calm determination.
We all knew this was the price of our support, some of us here thought it worth paying, others in the UK never did.
I doubt this will change many opinions in either group.