@ sooth sayer,
"If the standard for police should be that they can't arrest someone till they have actually committed the crime - we should ban all intelligence gathering, beef up the police and wait for innocent people to be slaughtered before we dare accuse someone .."
Ouch bad argument to put it mildly.
First off the police are set up and designed to be used as a reactionary / preventative organisation to protect society not the other way around.
That is they should only be used to arrest people either "as they commit" or "after they commit" criminal acts and at no other time, otherwise it undermines their standing in society which gives rise to real National Security issues.
Other "organs of state" are supposed to do it the other way around and "nip it in the bud" "just in time" or even alow lesser evils to prevent greater evils. This is what the so called "domestic intel" organisations are supposed to do.
For many years in the UK there was a semblance of balance and propriety on these roles and it (appeared) to work well.
However with the "Irish Problem" and "Special Branch" the Police role started to change. This was a political choice not an operational choice by either the Police or Intel community.
What has become apparent is that the closer the Police and elected representatives become the worse things (apparently/visably) get.
What is by no means clear is if it is cause or effect, or other changes in society (such as the availability of technology).
Personaly I would like the line between the Political asspects of the state and the judicial aspects of the state kept very clearly apart and the role of the executive to be subject to truly independant oversight (yes I know it's at best fraught with problems).
However where it all starts to get very messy is when it involves the many facits of "National Security".
For a number of reasons threats to NatSec are by no means "criminal" in nature nor political in any form and are often "broad tail" issues.
Even when some asspects of a Nat Sec threat are criminal, a larger part of the threat may well be not. Which is a problem with non political issues such as organised crime.
Further you then have other NatSec threats which are semi-political in nature and also involve crime such as "terrorism".
Moving through to political activities that are not criminal in nature and are not NatSec issues, but those politicians currently in charge see them as a threat to their position and want them treated as criminal acts and thus decree them to be NatSec issues...
For obvious reasons we need to deal with serious organised crime, and commercial activities (monopolistice cartel etc) that are real NatSec issues as well as terrorist organisations.
What we don't need is politicaly inspired curtailment of non NatSec and otherwise legitimate activities.
It is a very gray area and needs to be carried out in a manner that is clearly seperate from both the Political Government and the general enforcment of criminal activity by the Police.
Unfortunatly these activities by their very nature are difficult to legislate against and we have very messy "anti" cospiracy / monopoly / cartel etc legislation that is based on "percieved intent" of those under investigation. And as is currently seen the legislation is used not for it's original stated intent more often than not (war on photography etc).
Investigating "anti" crime is very difficult at best and is an area ripe for turf warefare, political patronage and lack of clear oversight by the judiciary. How we go about it says more about the society we live in and the lack of morals of those we elect than most would care to think about let alone admit.
In this particular case involving the Police under "anti-terror" legislation was to put it mildly a significant mistake by both the senior Police officers and Politicians involved.
There where better and easier ways of dealing with it. The majority of those arested where in the UK on student visas, and it would appear that most where clearly in breach of the terms and conditions of such visas.
As and when their usefulness as "Intel observation targets" was over a simple series of visa violation raids would have pulled them into custody (as well as a good few others as cover).
The heavy handed tactics deployed by the Police have (possibly) destroyed the Intel value these people had and if actually those involved with terror plots alerted those that control them.
As has been noted in the past a lizard can shed it's tail crawl under a rock and live to fight another day.
If you want to kill a lizard you have to seperate it's heart and brain, usually by chopping off it's head.
Entering into a war of attrition by repeatedly chopping of the tail will make the lizard smarter and the tail so short it will be difficult to find. Each of which make it even harder to kill the lizard...
But in this case it appears worse in that the police thought the "worm" the lizard was about to consume was the lizard's tail, so the lizard has got smarter without lossing any part of it's tail...