The London bombings are a tragedy. I was deeply saddened to hear of it, so soon after their Olympic triumph. London is one of my most-visited cities since I was a child. I was planning a trip at the end of this year, actually.
On the bright side, this will give them some insight as how to rebuild the transport system. Certainly, backup power and announcement systems, more robust security measures and civilian training for emergency situations would help.
What won't kill London will, make them stronger.