St Trinians?

I have just watched the Alastair Sim comedy The Happiest Days of Your Life and have yet to see his St Trinians movies. I'm not sure what to expect. Given Sim's excellent film career, St Trinians seems an odd venture...

A brief Google image search yields soft core teen porn images that seem somewhat poor taste. The actresses may not be teenagers themselves but the aim is clearly to portray teen girls in a sexually provocative manner. Why bother? For whose entertainment?