Not really. I live in Zone 4/5 West London (postcode TW area), and kids as young as I'd say around 9 or 10 are getting themselves to school on buses, trains and tubes every day. Not much different to my day - I was taking myself to school around 7/8 years old living in a small (10k pop.) semi-rural town.

After school they're getting themselves home as well, often in groups causing the traditional nuisance in newsagents and supermarkets (thank god the energy drinks are now not sold to kids!), and going to parks and whatever.

I think they have to be a little older to confidently get their way into Zone 1 on their own if they should need to, but I regularly see youngsters I'd guess are 11-12 years old going into town on their own, clearly to meet friends.

Despite what the media (and for crying out loud, the US President), says, London is actually a remarkably safe city. Murder/homicides are at a low they haven't been at for decades (possibly centuries), and while sexual assaults are rising, that is seen as mostly attributable to more reporting (victims coming forward more). In the case of assault on a child, that's more likely to occur in a family setting than it is in a public place during daylight hours.