http://www.education.gov.uk/publicat...employment.pdf
It is illegal for a child under 13 to be employed, unless
by a parent
and in an agricultural setting when they can do "light work" at 10
Check out page 11 particularly, where discotheques and places of entertainment are expressly forbidden
Interestingly, however, they can do so if the entertainment is provided entirely by children and that's where the 'performance licence', comes into play
Independent enterprise (i.e the car boot) does not appear to be regarded as employment, although the usual rules regarding 'invitation to treat' and contract to buy/sell apply to all minors. They must also not collect money without the supervision of an adult.
Chores around the house for pocket money is perfectly acceptable, but anything else places you on a sticky wicket.
p.s I'm not a childrens rights fanatic (if I had my way they'd still be up chimneys !!
) but they do need protection, as do their guardians