See the triler here..St Trinian's, a school for "young ladies" with its anarchic doctrine of free expression, brings together a motley crew of ungovernable girls who, using their wit and ingenuity, save the school from bankruptcy....IMDB
http://www.sttriniansmovie.co.uk/sttrinians.html
It looks like we have lots of overage schoolgirls, but with schoolage ones thrown in as well by the looks of it, so its not all bad!