@FreeDuck,
Got friends with kids somewhere near his age? If so, can you get out and about with them...you know...picnics, adventure playgrounds, barbecues....stuff like that, where the kids all hang in a group and run around?
Any clubs/groups around that he is interested in?
Any sports?
Get out to parks and playgrounds such as a family....I know when I was little, if there were kids anywhere near each other, we'd end up hanging together.