Anjem Choudary is currently in the news. With the likes of him and his supporters I'm not sure I expect much else. I'd prefer it wasn't done, but even with that we still have bombs and vehicle rampages. What are the alternatives?
The key difference is between "surveil known idiots like Choudary" versus "surveil everyone then try to find terrorism by keyword match". The latter is not only unlawful and unjust but produces a huge number of false positives.
Not sure why that comment's been voted down. Ultimately it's a question - voting down a question... Anyway, I'm not convinced surveilling the high profile people is going to alert you to the people who are off the radar, ie lone wolves. There might be an association between some, but not all. Again, (I think some people struggled to read this in the previous comment), I'm not pro-mass-surveillance, I'm just not convinced that what should be a better situation would be a better situation, ie maybe an unfortunately necessary evil.
Sadiq Khan has said he believes the threat of terror attacks are “part and parcel of living in a big city” and encouraged Londoners to be vigilant to combat dangers.
That is not what he said, but certain right wing groups enjoy peddling this lie so much that the London subreddit has an automoderator config that corrects people [1] whenever it surfaces.