1. 12 attacks havent been stopped. MI5 have claimed this, but havent produced any evidence to support it. You CANNOT ask for more surveillance powers based on someomes word there has to be evidencd. Without evidence, how do I know that they aren't just talking out their arse, trying to keep people scared in order to justify their own pay packet. I dont trust a damn word they say after Snowden.
2. No evidence to suggest that more surveillance would equal more safety.
3. Even if there was, you are basically asking people to give up the very essence of what it means to be free, in order to be safe. Would that even be worth it? Maybe you would be safe, but you wouldnt have a life. You couldnt safely oppose or challenge what the government said as they would always be watching every minute of your life. You couldnt safely discuss and explore different ideas for fear that your discussions would be noted down, and then taken out of context and used to persecute you. Would being safe be worth it if you had to give up the very essence of what it means to be free?