When I lived in London there was an old disused airfield that had be set up to contain roads, crossings, traffic lights. In fact most things you'd find on a normal trip out.
Anyone was allowed to drive under supervision as long as they could reach the peddals. Think I was about 10 at the time so I'm going back a year or 40.
There was however plenty of disclaimers sign posted all over the place. It was an excellent place to learn and my mates Dad used to take us there every weekend. I put that experience down to helping me pass my test first time a week after my 17th.
Ahh, those were the days :)