In reply to fmck:
My three kids are now wearing the following:-
Eldest daughter, tall, slim 12 year old - Womens XS BD Primrose, fits her well and looks and is grown-up
Middle daughter, tall skinny 10 year old - Kids version of BD Alpine Bod which was given to us - she loves it, says it's very comfortable
Youngest daughter, small 8 year old - Edelrid kids sit-harness, can't recall it's name. It fits her just, she is small and the waist is cinched down to it's minimum. Harness appears to be decent quality but it is inclined to twist and kids (I've handed it down from child to child) don't find it easy to sort out and put on by themselves.