Consider the following, from Reuters today ("Blasts hit London again, 2 weeks after bombings":
"London police chief Ian Blair told reporters: 'We know that we've had four explosions or attempts at explosions. It is still pretty unclear what's happened. . . . The bombs appear to be smaller than the last occasion.'
"He said some devices appeared not to have gone off properly and only one person was injured, adding that he hoped London would now 'get moving' again."
This does not sound like the kind of well-planned and -coordinated attack that occurred two weeks ago.
The Reuters report noted that a witness at the Oval underground station in south London reported what appeared to be a would-be bomber alone in a carriage after a small blast:
"We all got off on the platform and the guy just ran and started running up the escalator. . . . He left a bag on the train."
Again, this is very sloppy work, and it is not clear whether this bomber intended suicide.