For all the CCTV in London I've been mugged twice and nothing was captured on CCTV nor were the police all that interested in doing anything about it. As an outsider living here I think the UK has huge social problems that are neglected in favour of retaining classism. America has the same problems but at least it's more "ah, what can ya do about it huh" rather than "we are a perfect polite society British values bla bla".
no. you cannot. ever.
even if you have perfect faith in current government, you're one election away from something different.
CCTV is also extremely ineffective in crime prevention in general, and actually catching criminals - one of few studies(back when i did write my thesis on subject related to it) used different areas of UK to measure crime fighting capability and effect of CCTV - by finding similar areas with and without CCTV and comparing crime statistics.
they only worked on parking lots, there was no measurable differences in plazas, alleys, roads, highstreets etc.
and a bit of anecdotal evidence - once cameras at my older workplace caught robbery to a place next door. With criminal looking directly at the camera, before bashing the window with a brick, jumping in, and hopping out with accomplice. They never got caught. This was quite decent camera, with face clearly visible - i know this because we directly cooperated with police.
It's human to help your friend because they're in need; that's how tribes work. But it's just as human to disparage or sabotage someone who isn't a part of your tribe, to not care about them. To lie and cheat and be corrupt.
As for police effectiveness; there are shady groups of people that hang out in dark alleys in some central London areas every single weekend. You need only walk around/down the wrong place to meet them. All it takes is sting operations where a plainclothes officer acts drunk and hits a "get 'em, boys" button to bring in the fuzz when they inevitably get attacked.
There are all sorts of socio-economic-political issues that contribute to all this, though. But the root problem is in the apathy of the general public, none of us care about anything unless it affects us personally.