Not been checked for the number but i have seen others checked.
Your son will need to be 16 or at least look it...........mines 14 and doesn't act 16 so can't go on track and he would love to but will have to wait........he is the one who is collecting reg numbers for 3dr sierras - i have spoken to you on the RSOC and he met Karting at Stanford hall last week and looked at his 500 for ages.
I can't do nat day on track but might get there to look round - croft looked a good day last year so doing that one.
Most people do airfield days near me as they are safer and cheaper.