The terrorists responsible for the London and Glasgow airport “car bombs” are my favourite kind: bumbling idiots who could not explode a jar of nitroglycerine. I feel a lot safer,knowing how incompetent they are. My main worry is that some of the suspects are doctors: if they planned this, how did they get through medical school?

There is an excellent article on why the bombs did not work, but a former bomb disposal expert, at The Register. To sum up the argument, unless mixed with an oxidiser, both petrol and inflamble gases tend to produce rather weak explosions. This is why cars have carburetteurs. I can think of better ways blowing things up with a few minuted thought.

There is a very good reason why, when the RAF are asked to bomb somewhere, they load their planes with bombs containing proper explosives, not with cylinders of gas. The latter simply do not produce much bang for the pound.

Fires involving cylinders of gas happen, in London alone, about once a month, according to the London Fire Brigade. They sometimes explode, but not always: even the cylinders in the Jeep used to ram-raid Glasgow airport failed to go off. Even when they do go of they rarely kill people.

Even if the cylinders has exploded, what would guarantee that they would explode together. They would have produced a series of small explosions, rather than one big one, and the consumption of oxygen by the first cylinder would mean subsequent explosions would not even have oxygen to feed a fireball.

In fact the cylinders, even if they went off would probably not have exploded. They would have been breached at one point, and the burning gas rushing out would have sent the cylinder hurtling through the air. This is what often happens when gas cylinders in a burning building do go off: nasty if it hit someone, but nothing like as dangerous as a bomb.

Think of all the things these terrorists failed to do. They did not buy or make real explosives. Why not? Did they all fail chemistry at school? They did not ensure that the materials they did use were mixed with an oxidiser, or, in two of the three cases, even ignited. They did not even make the best use of the materials they used: have they never heard of Molotov cocktails and flame-throwers? I will not elaborate further because I do not want to give any thicko wannabe terrorists who might be reading this any ideas.

I have seen what competent terrorists with a real car bomb (actually a lorry full of explosives) can do. That was worth worrying about and genuinely scary. This is not.

This lot were also not very good at covering their tracks. Despite apparently not having been previously monitored by the police, they were all rounded up in a matter of days. What happened to the classic terror organisations divided into cells, with no one person knowing too much? This lot were merrily phoning each other up, so their network could be analysed by pressing a few buttons on telecoms companies computers.

My own explanation for what happened is that Al-Quaeda realise that a major attack would create sympathy for the victims. Remember how everyone was on America’s side after the “9-11” attacks. Al-Quaeda were lucky that the Americans blew it by invading Iraq. They know they might not be lucky the next time.

On the other hand they want to keep up the pressure, keep people uncertain and firghtened, divide British society by making people suspicious of minorities, and keep themselves in the news. Encouraging groups of people who are:

• not valuable to them, and
• not capable of mounting a major attack

to hatch silly plots like this and the liquid explosives plot (which also probably would not have worked) lets them keep up the pressure without causing real damage.