@shri most crime is between gangs and criminals, or of a domestic nature. Even in the worst neighborhoods there are very few cases of an outside person coming in and being killed. Maybe robbed or pickpocketed but if I recall in London the borough with the highest theft rates is Westminster. Yes be aware of surroundings but the idea that any white person in a black neighborhood is going to be attacked is false. Black people living in the black neighborhood are the main victims.