Working class and upper class children seem to have this freedom in London, having lived in both to press of area.

When I lived in Richmond there were often children alone on the bus or train with expensive belongings like musical instruments or sports equipment. My middle class parents would never have allowed that - but they would expect me to get to school on public transport alone.

Also, there are no rules or laws against this. It's cultural. See http://www.btp.police.uk/advice_and_information/travelling_s... for one example - there's no minimum age to travel alone on a train.

There were a couple of highly publicised cases which I suspect may not be accurately reported in the newspapers, but generally UK child protection is under-funded and errs on the side of non-intervention. Which has tragic consequences of its own: Victoria Climbie, "Baby P" and so on.