On the surface, Ongar appears an unlikely site of innovation. Sometimes known as Chipping Ongar, the sleepy market town in the Essex countryside has relatively few claims to fame: it features in a Will Self novel, boasts an aged wooden church and was once home to the furthest London Underground station north-east of the capital. But on one of the town's pleasant residential streets, a children's home, virtually indistinguishable from the houses surrouning it, plays...