I haven't read all four pages of this thread, so apologies if this point has already been made, but it has occurred to me that in foiling this threat before a half dozen aircraft are lost in mid-Atlantic, the UK police are victims of their own success.
My point is, most people, and quite a large slice of the media, will react to this in the same way they have reacted to the recent 'chemical lab' raid in East London - criticising the police because they didn't find anything.
My prediction? Some slick lawyer will get the people arrested off from most of the charges because there won't be sufficient proof for a court of law, and the poor bloody plods will get no credit for possibly stopping these people before they could carry out their plans. Ask yourselfd what the world's reaction would have been if the US authorities had arrested all the September 11th hijackers at the airport and stopped them befor they carried out their plans? Well meaning US lawyers would have had every one of them released within 24 hours.)
I said it after the East London raid and I'l say it here again - the bad guys don't have to actually carry out these threats any more. They could damn near finance their terror organisations entirely by sooling police onto some of their mates who will make a point of having absolutely no incriminating evidence in their homes and then sue the police for compensation for wrongful arrest.
In the meantime, they achieve their aim twofold:
1. The public get more disillusioned (and disbelieving) with the constant (false?) calls of 'wolf' by the police, and
2. The disruption these 'false' alerts cause is almost as effective as the act itself.
PS: I hadn't read 'warkman's' post when I wrote the messsage above, but it would seem he's proven my point.