Dear The People,
Under our current system of law, we tend to require evidence of wrongdoing before we can imprison someone. There are tens of thousands of extremists in the UK right now, only some of which will actually end up killing people. Precisely how do you intend that we monitor these people without something like bulk surveillance? Or should we just lock all these people up without charge?
The reality is that you know someone is dodgy, and you know he knows dodgy people. Unless you have concrete evidence that he's about to murder a bunch of people, our current innocent-until-proved-guilty system says you cannot just throw him in jail. By the way, according to the police anyway, this is lost 2, won a dozen or so, in that they "disrupted" about a dozen terror plots in the last few years.
And anyway, we are talking tens of thousands of people here. We'd have to build a few prisons just to hold them. And if we start engaging in the habitual internment of Muslims in the UK, how many more extremists do you think that will generate?
I don't know what the solution is, but some kind of automated surveillance is going to be necessary because of the sheer numbers of Islamic extremists involved. If there are 10000 extremists, and each needs a team of five (absolute minimum) to watch them, on £50000 each (salary, pension, equipment, cover, etc.) then that's £2.5bn. And that's to employ 50k people just to follow them round. It's not feasible.
And we cannot deport them because most of them are British citizens.