10 schools in 3 countries, so it varied. But essentially started travelling on public transport alone at 11. New school, where I boarded, but at half term on my parents instructions, and with my younger sister I went down to the bus station and caught the Newbury bus, via Compton, where we got off at the bus stop outside our new home. Next time we did it by train and walked from the station.
By 13 I was travelling from Reading to London by train for dental appointents at the Dental Hospitla in Leicester aquare.
At 15 sis and I were deposited at Heathrow airport to travel out to Malaya, nominally under the care of a stewardess, but mainly left to our own devices. We dealt with plane breakdowns, overnights in strange hotels in previously unvisited countries and Custom men who wanted us to open all our Christmas presents in the customs hall on December 20th.
DC first travelled alone at 11. We moved into a big town as I returned to a fulltime job. On our first day in the house, I walked DC (9,11) into town and bussed them back. After that DS 11 could go out and travel alone, but 9 year old could only go out with brother, At 11 made his first train journey alone, 3 stops down the line to a friend where we used to live.
DGC live in a city near a main road with a frequent bus service. They have been using local transport since they went to secondary school.