Thanks for another excellent post.

I'd just like to make a couple of points:

First, all exams are blunt tools to a certain extent. IQ tests are similar to the old 11+ exam because both depend on cultural knowledge of middle and upper class so-called general knowledge. Exam takers from working class and long-term unemployed parental backgrounds will score lower.

Second, teaching at a grammar school would have been a much more satisfying job than at a secondary modern or at a comprehensive school, not just because of pupil motivation and their intelligence, but also because of higher behavioral standards at grammar schools.

Third, parents tend to send their offspring to private schools in the UK because of improved behavioral standards from comprehensive schools, not because the teachers at private schools are deemed better.

Another point, this time about the German educational system, is that its very hard there to become a teacher, much harder than it is in the UK.