Surveillance? Does it work?

The suspects in the latest UK terror plot had been under surveillance for a year apparently. How much does that cost? Alot I would imagine. We have been told that the police and MI5 are stretched to breaking point and tracking (depending on which news you read) dozens and dozens or over 70 different plots. Each one of these has surveillance teams presumably working around the clock.

It's come to light that the surveillance of the suspects in last weeks 'foiled' alleged plot had not turned up the pertinent fact they were going to bomb planes. (This came out through interrogation in Pakistan of another suspect). You'd have hoped after a year of surveillance including a mole within the organisation that they would have come up with the bombs on planes part right?

Then there is Forest Gate where two brothers were arrested (and one shot accidentlally) recently and no evidence of anything untoward being discovered. These two had been under surveillance for quite some time so much so the local residents told reporters it was well known in the street that surveillance was going on as the police although staking out in an unmarked vehicle, continued to wear their uniforms. Nice one guys!

So my question is wouldn't it be far better saving all that money and man hours on surveillance operations which seem to be, well, a bit rubbish really and instead once you get a sniff of a plot then call the people in, tell them straight 'we know you're up to something so you can stop it now' and then put them on a kind of parole or something similar where their movements are more visible and as they have been 'flagged' will show up far more easily in the system if they try anything funny.

I don't see how your idea is different from normal surveilance.

The key in surveilance is to ensure you are watching the right people. In order to do that, you need a damn good reason. general surveilance of the population is pointless, invasive, and uneffective.