Westminster is "special" in that it is very dense, has a lot of violence compared to its affluence (due to the amount of nightclubs and bars etc) coupled with a massive amount of high priority buildings, and the combination of that means that it has far more government controlled CCTV than pretty much anywhere in Britain outside of City.
Westminster and City are probably the two small parts of London where there'd be a reasonable chance of "total surveillance".
But even Westminster is also chock full of CCTV dead zones due to the narrow streets and complicated building facades with lots of nooks and crannies - it might be "easy" to get coverage of people moving along the streets in Westminster, but incredibly hard to eliminate opportunities for people to hide away.
Westminster and City are probably the two small parts of London where there'd be a reasonable chance of "total surveillance".
But even Westminster is also chock full of CCTV dead zones due to the narrow streets and complicated building facades with lots of nooks and crannies - it might be "easy" to get coverage of people moving along the streets in Westminster, but incredibly hard to eliminate opportunities for people to hide away.