Easy, perhaps I'm overgeneralizing, but sounds from your descrip that even London's W End is far more dangerous w/street crime and vandalism than Manhattan/SF's upscale office/residential corridors....

Will admit I don't really walk anywhere ; have always enjoyed comfort and safety of driving own new car for even my usual <2mi intra-SF commutes...and always have been paranoid enough re: personal security that I typically drive from point-to-point within SF w/secured garages@home&office/valet pkg directly in front of my usual dining spots.....and to-date have never personally faced an incident of street crime/vandalism and haven't heard of muggings from affluent pals who actually occasionally walk around SF/NYC....

On the bright side, given that my elders tell me NYC was much more dangerous w/street crime 20-25 yrs ago (and remember that US has a deep-seated, casual use-of-guns culture ) , perhaps London is going through a similar temporary ugly phase before it also "cleans up" like NYC/SF/Chic have, esp in the relevant urban office/entertainment/residential epicenters where the affluent congregate....where street crime is a fairly rare phenomenon today...