ANALYSIS: The attempt yesterday to inflict more terrorist destruction on London appears to have been either a cack-handed copycat effort by relative amateurs or an assault similar to that of July 7th that went mercifully wrong.
In either case, it is already clear that the police got a lucky break yesterday - a break that may help them track down the perpetrators, be they amateurs or al-Qaeda fellow-travellers.
First the similarities.
Pattern has been shown to be an important factor in al-Qaeda attacks: repeated use of public transport (aircraft in the United States, trains in Madrid and London), and timing (simultaneous bombs in each case).
In both London incidents - the one a fortnight to the day after the other, although at a different time of the day - the targets were three London Underground trains and one bus (in both cases, the top deck of a bus).
According to the Metropolitan Police, the attempts to detonate four bombs yesterday were simultaneous; the July 7th bombs exploded at almost precisely the same time, killing 56 people and wounding 700.
Yesterday's failed explosions also replicate to some extent the north, south, east and west pattern in evidence on July 7th.
Clearly the mere fact of a second terrorist incident, albeit an apparently failed one, two weeks after an appallingly successful one gives rise to an assumption that they are connected in that the same people, or linked individuals, are behind both.
But what of the differences?
Looked at another way, there are some indicators that the two events may not be linked.
Yesterday's bombs appear to have been far smaller than those of July 7th.
It appears that only detonators went off, suggesting a less "professional" operation than on July 7th.
There were suggestions last night that at least one of yesterday's devices was a nail bomb. A crude though effective bomb, it is far less effective than those detonated on July 7th.
But the main difference between the two incidents is that yesterday's failed.
This suggests that either yesterday's attack was perhaps a suicide mission that did not work (was each bomb assembled by the same person who made a mistake with each one?), in which case it is strongly similar to July 7th.
Alternatively, it was an attack carried out by less "committed" terrorists and which, because of their relative lack of of skill, was a failure.
In the latter scenario, the perpetrators could be amateurs or copycats.
In either case, the outcome of yesterday's attack is good news for the police.
They now have a wealth of information from the bombs that failed to detonate.
From these, the police will learn much of the level of competence of the bomb-makers and, more than likely, they will also obtain forensic evidence - fingerprints or fibres or purchase details that may lead police to where component parts were bought - that could lead to arrests and convictions.
And so also could eyewitness testimony, of which there is a wealth from yesterday's incidents. Many people saw the "bombers" flee and in one case it is reported that people pursued and tackled, but failed to hold on to, a bomber.
Police success arising out of yesterday may help bring Britain's intelligence services more up to speed on the threat facing the UK. But al-Qaeda is a loose network bound together by an ideology.
One or two lucky breaks will not diminish the threat in the short term.
