Final year of UK junior school is ten years old. By eleven, I was taking the train to another town for school. With a few other children, but no adults.

I think the acceptability of this stuff comes down to the area you live in.

Yep, where I am this is completely acceptable also, although not as common as it should be... Often because of judgemental people like you scaring off parents. Children are more capable than they are given credit for in many (mostly US) circles. It also seems that global news has distorted adults' risk calculations... Statistically the biggest risk to my children right now is probably obesity... Which I offset by making sure they have some freedom to roam outside of the car.

I walked myself to school at age 5. By 10 as in the GP comment, I had a fairly long walk up a hill. By 15 I walked 4.4 miles to school some days, most days I caught a bus. In retrospect biking would have been better. What about you?