London Subway Attacks II

Today saw some more subway attacks on the London Tube. Despite being a carbon copy of the attacks two weeks ago (three trains and one bus), no casualties were reported as only the detonators blew up. Although the police are reporting the attacks were serious and "meant to kill", I can't help thinking otherwise.

To have four bombs fail to explode is unprecedented as far as I know. Usually if the person making the devices were an idiot, one would expect variable quality in the bombings, ranging from a reduced bomb explosion to no action at all. But to have two to three detonators going off (the number is uncertain at the time of writing) without an explosion indicates something else has happened besides mere incompetence. Another strange detail is that the bombers are said to be surprised that they survived the detonations when previously the police were thinking that the original bombers were tricked into becoming suicide bombers.

My feeling is that today's bombers were actually pranksters who copied the pattern of the earlier attacks as an excercise in sick humour (for which the police should help them down the stairs as much as possible when caught). Much will depend on what comes to light as solid fact instead of the scuttlebutt currently being reported. For example within an hour of the attacks, one of the bombs was being reported as a nail-bomb. How could people tell that if it had failed?