No point in giving too many plot details here, just take the basic premise of an all girls school being assigned to an all boys school by mistake, add that on the same day the girl's headmistress has to show a group of visiting parents around while the boy's headmaster (who is due to be promoted to a senior position at a new college) has to show his new employers around and I think you'll get the picture.
This fifty year old comedy wears well. The pace is frantic, like a French farce with doors opening and closing and much dashing along corridors with split second timing as the two groups try to avoid each other. Magaret Rutherford and Alistair Sim ham it up superbly and there are many familiar faces in the supporting cast, all of whom react with great professionalism. At ninety minutes the film doesn't out stay it's welcome, and there's even time for a little romance that doesn't slow up the action one bit. Incidentally I had forgotten how sexy the gym outfits of English schoolgirls of that period were. It bought back memories.
