Friend of mine with a 12 year old girl and 9 year old boy, have in the in the past had holiday child care via grandparents. Grandparents are now too old. They have taken to leaving them at home all day, 8 to 6, with the 12 year old girl in charge. What is the law on this? I thinks its a lot to ask of the girl. She is sensible and mature, but its a lot of responsibility for someone who has just started secondary school.