As far as the "incident" is concerned I agree that this is just one of those things that happen in high concentrations of people.
Originally a west Londoner I have lived here since Nov '11 and neither my teenage kids nor I have experienced any crime to date. We love the facilities that Forest Hill has to offer and feel that the regeneration of Dartmouth Road is making a huge difference to the feel of the area.
I do however feel that the speed some people drive around the back streets is quite astounding. I live in a 20 mile an hour zone and regularly have to dodge cars rocketing at 60 miles an hour... I would happily buy a speed camera MYSELF and donate the profits to a children's charity!!