"they failed to notice the Kouachi brothers quite open pre-terrorist behavior & planning.". Well they knew about them but as somebody in the French police pointed out it's just not possible to assign people to follow each step a suspect takes for the rest of his life among say several hundred similar suspects. The simple solution, a very old one, would be to just jail them or shoot them as suspects. No need to point fingers towards any specific country her.
I don't think we want such an society. Cameron of course will look for a fast solution not to look undecided. Understandable perhaps but rubbish all the same.
The solution, as before, is education, there has never been any other working solution, but imagine a politician brave enough to mention anything like that when the "soul" tells him he has to have a solution now.