Sorry Bernie, but I have a bit of a problem with the way you went about that "argument"...
I don't see why 'who benefits' is the starting point. Taxi drivers benefitted because more people avoided the tube? Paris benefitted because more tourists avoided London? There are examples of people doing things (eg terrorists) that backfire on them - that hurt their own cause. I could make a whole list of people, interests or causes who benefitted or were hurt but I can't see why this is the "starting point", especially if the question is "who did it". Surely the starting point is the evidence - witnesses, forensics, cctv and so forth.
You then mention past form and bring in the Italian secret service. Again, why not bring in Aum Shrinrikyo (Sarin attack in Tokyo) or any or every personality type, cult, groups or organsiation that has been involved with violence? You jump directly to extremists at the fringes of secret government agencies. If you are inventing peope why not just invent random nutters who like setting off bombs?
As for the fantasy world of government agencies that can seemingly easily persuade people to go and kill themselves, somehow get loads of normal British people who work in various public sector jobs to take part in mass murder as if they were all working for the gestapo - sorry, but this is utterly bonkers as well.
I know you are just doing a thought experiment, but this isn't a "strong case" scenario IMO.
A strong case scenario would be more along the lines of "let's just sit and watch these guys, let them operate in the UK, let them do all sorts of stuff, because they are not going to attack inside the UK" - the same kind of attitude that the police take to drug delaers or prostitution - ie don't bother with the small fry, hope that they lead them to the key players, try and keep them 'contained' and 'under control'.
From this point of view the lie would be that this was the actual policy (they would want to pretend that in fact they had "zero tolerance" of Islamist terrorists) and cover up would be after the fact - agencies trying to avoid getting the blame for fucking up by concocting a "they came out of nowhere - it was all masterminded in Pakistan by the big bad kingpins" story).
This strong case scenario doesn't need shadowy neo-fash figures working for the americans and persuading young guys from leeds to go and blow themselves up.
ps as for the train time stuff: I've noticed that the 0748 train was scheduled to get to KingsX at 0820, whereas the train that actually arrived at 0820 was the delayed 0724. If someone simply assumed at some point that the 0724 train was the 0748 train (because it arrived at 0820) then this would explain why everyone was reporting that they travelled on the 0748.
They were seen at Luton on cctv at just before 0722 (assuming the cctv clock was correct) so could have got on the 0724 - people have said it would be impossible to run and catch the train, but anyone who uses trains knows that the platform guards often wait for people running to catch a train especially if the service is all screwed up anyway - so unless there are actual witnesses the 0724 departure time could be a minute or two later as well - enough time to get it.
The 0724 arrived at KingsX at 0820, they were seen on cctv at king x at 8.26 and the tubes left at 08:35, 08:42 and 08:48 meaning they had time to get on them.
I hope that this particular crock of shit can be finally laid to rest, although of course it would be vene better if someone could go and check all these timings, speak to other people who were on the Luton to Kings X train and if some of the 0826 CCTV footage from Kings X was released.
edit: Hmmm. This is kind of turning into a conspiracy thread isn't it?