London isn't a city, it's an amalgamation of small towns all joined together. Some parts are perfectly safe, others are feral, especially if you happen to be a youngster and in the wrong area. I've never had any issues there apart from one occasion when ironically a coked up banker type thought he would create because by missus was a model.
I grew up in a market town. You had to be hard if you wanted to go out drinking then. Mind you back then usually the worst that would happen is you get ten shades of **** beaten out of you if let the other guy get the better of you. Stabbings and robberies were virtually unheard of. Now both are common.
Manchester is the same but it’s still a city.