I’m happy to take your word about that, the less I know about explosives the better. But I don’t see any difficulty imagining that they knew what it was right from the start. I don’t think anyone is questioning that there is information management. On your general theory, I think it comes down to this: are the British police there to protect us, or are they out to get us. Using - as you recommend - Occams raisor, I’ll stick with the former view.

?Police believe that explosives…” Forensic determination between HE such as Semtex / RDX and something like TATP is, with on site portable spectrophotometers etc., a piece of piss and takes minutes. It is like the differenc between mayonnaise and Dundee fruit cake mix. “Police believe…” seven days after the event? Forensic scientists KNEW the same day with 100% certainty. They could likely tell the factory of manufacture and which day / shift it was made - which if you doubt can be done, is a feature of the UK passport by the isotope mixture used in the glue sealing the binding which changes every shift - which also has to o-ordinate with the batch of double sided colour coded adhesive used to attach the photograph.

For some different thinking on the bombings see http://www.williambowles.info “Dead Men. Tell no Tales” and http://www.postmanpatel.blogspot.com