Where are all the children?

It occurred to me today, as I pressed through the crowds at Clapham Junction and London Bridge (it is amazing how crowded London is in the summer), that I was feeling a little like that scene in Chitty Chitty Bang Bang in Vulgaria, when Dick van Dyke realises there are no children.

Where are they all?  In the suburbs?  In the countryside?  Locked into airless, artificially lighted New Labour-style nurseries, enjoying their interactive education smart screens?  I don't know.

There are one or two...