As a prudish male of 75, I thoroughly enjoyed this movie. Not least because it is one which is so 'English' as to be incomprehensible to Americans, and impossible for them to make. If a little stereotyped, and I don't admit it was, never irritatingly so. In fact, the sparkling originality (of treatment, not theme) of the film mirrors that of the teachers' methods. No cheap humour, prat-falls, or custard-pie humour. The homosexual scene involving Irwin and Dakin near the end is neither funny, shocking, nor relevant, and in my opinion should be cut - it destroys the carefully built up sense of credibility of the rest. It is disappointing but predictable that a film of such quality and courage, the audiences are scant and aged.
Another small criticism is the choice of WWI and II for the students' profundity of discussion - 'scholarly new angles' to them are very old hat to those in the audience who have firsthand experience of them; it might have been wiser to have picked Agincourt or Trafalgar. It's a long while since my experience of high-school, and it was never like that, but the fine construction, directing and acting well succeeds in imparting realism to a difficult combination of intellectual humour and fantasy.