Is it unusual for school to use a sixth former as a group leader on residential trip?

I also think other posters have totally missed the point!!!

I think there are grave problems with asking a child at the school to be a supervisor on a school trip, especially a trip abroad. Although in law there is no minimum staffing level for trips, most local authorities produce guidelines on such activities. This is because there is a risk and it is totally unacceptable to load this risk on a child. It is the role of employees of the school. They can also appoint responsible adults to help who must be CRB checked. Most people would not think a responsible adult was a 6th former at the school even if they are very sensible. If I was the parent of the 6th former, I would not allow my child to be put in this position. They are in loco parentis whilst on the trip and can be sued if anything went wrong. The 6th former is not in a union. How would they defend themselves? This is utterly wrong and the Governors of the school should not allow this to happen. I would certainly take this up with the school. The 6th former should be allowed to go, but NOT as a supervisor.

I,m sure they would not take someone on who was not interviewed etc.

I was hitchhiking decades ago working and very responsible by 16, 17, 18.

If she has a problem with it, she could just go and ask about it...!

Friend is an economics teacher. He goes to
Rome every year with school kids. He never mentioned any problems.

DS had been to Malta, Manchester, skiing on school trips, always came back in one piece

I can see where your friend is coming from, a well trained teacher would usually be preferable. Although I would assume the school has chosen a responsible Sixth Former to be the group leader, and it's likely they will be even more worried than the teachers- which may make them more diligent.