We live in a quiet, safe cul-de-sac. My kids play out with the neighbour kids, there always seems to be a few out there if the sun is up. We all keep half an eye on them through the windows. 7 year old came in of his own accord because he wanted to go to bed. Asleep just after 8. Just dragged my 9 year old in to get ready for bed and she's complaining as her 7 year old friend is still playing out. First day of the summer holidays, they aren't doing anything in particular tomorrow. How late is reasonable?