Last week, Ahmed Hassan was sentenced to a minimum term of 34 years in prison. The previous September, he had stepped onto the District line of the London Underground and left a homemade bomb on the train. At Parson’s Green tube station, the device detonated. Fortunately for the commuters, which included many children on their way to school, only the detonator of the bomb went off. On its own, it created a fireball which ran along the roof of the carriage, singeing the hair of many passengers and causing an immediate stampede away from the blast and a number of injuries. The main explosive material the of bomb, however, which was packed with shrapnel, including bolts, nails and knives, failed to detonate. Had it done so, the United Kingdom would have seen — for the fourth time in a few months — dozens more dead victims, including school children, carried out in body bags.