Keep calm and carry on

Today’s assault looks reminiscent of one 12 years ago, shortly after the horribly successful tube bombings of 7/7, when another attempt was made to bomb London using homemade explosives packed into buckets. The detonators went off, but the explosives did not catch. This may be what happened today. If so, it is a tribute to the effectiveness of long, slow and unglamorous efforts to cut off wouldbe terrorists from the sources of the knowledge and skills they need to make an effective device. It is a tragedy that these attacks should come to seem predictable and almost routine.