I went to a very small primary school in small, very quiet village, we had 50 pupils, 3 classrooms (but only 2 were used as not enough kids) and no hall. Because we had no hall, assemblies, wet playtimes/lunchtimes, indoor PE, school parties etc were all done in the church over the road. When I got to yr5 (so 9/10) I and another girl who was a year younger than me(!!) were appointed church monitors. This meant that every morning we would go to the headteachers office, take the church vestry key, leave school grounds, go over the road, unlock the vestry door then go through the church and unlock the main door ready for assembly. On the odd occasion one of us was off school poorly, we'd simply do it alone instead of taking someone else with us. We had no supervision at all during this, we didn't even see the HT when we collected the key as it hung on a hook outside her office door! We'd be in class for the register then be like "Ok Miss we've got to go and unlock the church now" and that's it.
It was great at the time and we felt so grown up having this responsibility but I think I'd be horrified if my daughter was given a job like this to do. I'm only 28 now so it wasn't really that long ago!