Testing a bomb is hard to do surreptitiously. If it draws attention to you before you are ready to do the real thing, it wasn’t worth it.

And all fail in deployment? Sloppy work. They should have tested spares. And if they didn’t have spares, all the more sloppy work.

Yep, this is possible. The hiccup in Luton, or somehwere else, may have meant that had to use ‘old’ explosives.

This is one of the key issues, my guess is they weren’t, but you have a valid point if they were. I don’t know enough chemistry, and actually, in this context, I don’t want to. Both a little and a lot of knowledge are ‘dangerous things’.

“Why assume that the attack failed?”

Well, the reasoning behind this would be in the London incidents update post.

I can assure you that making a few explosives for fun is not that uncommon among students.

The simplest explanation is that this is another group at work.
It seems quite unlikely that the attacks of 14 days earlier were executed by the only group of like minded people in Britain. It is much likelier that there are several which cannot dare to coordinate due to persecution. In this case detective work is made only marginally easier for get only one group of several.
That would suggest that yesterday’s attacks were copies only in timing and exact targets and failed due to the rushed nature of the bombing.

Yes, well I think this is fine and understandable, in the end people’s lives are at stake. But you have to imagine that some at least of the would-be bombers are on the loose, and they may be feeling desperate. If they were intending to blow themselves up they may not have had a plan b. So who knows where they are, or what they are doing. Their photos can be released in any moment. This is like an old Thomas (Not Tom) Wolf novel title: you can never go home again.

In more general terms I think the UK administration is having to come to terms with the internet age. This really didn’t exist in the case of the IRA. With UK press they can stick what used to be called ‘D’ notices, but obviously means of communication elsewhere can speculate and release names, etc etc. This I think is a real problem for them. OBL will have his equivalent of Langley, and once a name breaks others will be warned. I think events in Egypt and Pakistan must have given particular problems. On the plus side, todays events should make the detective work inside the UK much easier.