I do wonder sometimes, with all the keyboard-warrior outrage at the Security Services' actions, what exactly people think they should do. General consensus appears to be that yes, we do need them, but it seems to me that people just want them to stay over there, don't invade our privacy or collect any information about us, but somehow magically know who The Bad Guys™ are and therefore keep Us Good People™ safe.
There's also the other angle of "okay, so they're collecting all this information about us, and for what, we still see bad things happen to Us Good People™", blindly ignoring the fact that bad shit is being planned and prevented all the time - those one or two bad things that do happen are unfortunately what slip through the net.
The good guys only have to fail once for bad stuff to happen. The bad guys only have to get something right once.