Over the last 150 years, the proportion of children has dropped steadily. In general, areas whose populations were growing fast would have contained a lot of children, because immigrants are generally young adults who then tend to have children.

Local concentrations of young people in 1851 and 2011 were surprisingly similar, focused on the south midlands with most of London lacking children. However, at the start of the 20th century high proportions of children were found in industrial areas, reflecting their recent rapid growth, and in some parts of outer London.