I agree that it is extremely important to report these things to the police
in order to make them aware where increased street patrols or suveillence (spelling bad...I know) is needed.
I was mugged in West London some years ago by three youths at 4pm,
I got dragged to the ground and despite screaming my head off and being a 5ft 4inch woman people just walked by, the muggers got my handbag
and to be honest I've never quite got over it-I still freeze if I hear footsteps running up behind me, or see gangs of youths in the street.
Dont let these people get away with it, report attempted muggings and threatening behaviour-remember that young teacher who lost his life in Sydenham just a couple of weeks ago?