No Rob it is probably sixth formers with a certified break, it is just that eighteen year old's today look like twelve year old's. I like the juxtaposition of the young with friends and the the elder's sitting alone on a park bench.
I like the composition and the near silhouettedness of it (I'm sure that's a real word - and, if not, it should be!). You don't see these warnings for Ninja death stars so often these days do you?!
I think the warning was about the trees. Can't you see them sneaking up behind the man sitting on the bench? First we had them jumping in front of RPF members when trying to take photos, then we saw them eating rocks, and now we see them sneaking up behind someone. I say we should ban all trees, for the children's safety if for no other reason.