July 21 attacks

I am just watching Channel 4 news' report on the background to the July 21 attempted bombings. The Police said that after they covertly filmed the bombers amongst 20 people at a training camp in the British Lake District they didn't keep the 20 under surveillance because of a lack of resources. Here's an idea as to where the Home Office can get the money to keep a very close watch on all the terrorist suspects they want to; scrap ID cards (and the National Identity Register behind it) and use the money saved to follow all suspected terrorists. How many police and security operatives could be trained and employed for the amount of money still to be spent on implementing this system?