I'd say your just being sensible.playing out in a visible field is fine but when he wants to come in just meet him by the lift/stairwell of the flats as I imagine that's where something could happen that would frighten him.I'm lucky that we live where we do and my boy is now 14 but when we lived at the top of west cross we let him out into the street about 8/9 yrs old and he could do a bit of local roaming when he was 10.We were lucky in a way that a built him a fully fledged summer house from scratch which I put electric/tv etc in and we had our own swimming pool under a conservatory so he wasn't lacking in things to do!!!!