Not sure about this - it's only anecdata but most primary school pupils I know are walked to school and I would guess most secondary school pupils (in London) get there under their own steam. Edit to add: the school admission process is already based on distance to school. Most parents would love to be 'made' to go to their closest school; the reality is those schools are often over-subscribed. I seem to remember a stat that most private car journeys within London are less than 2 miles. Most cars I see on my bike route into town are delivery/commercial vehicles.