Striving for Minimally Acceptable Standards
No. 2, I can't speak for CAA exams, but if they are anything like our Transport Canada exams they have little to do with actual flying and are nothing more than a hurdle to be got over, rather than a test of essential knowledge. Certainly they (can) do nothing to evaluate judgment, which is far more important than exam-writing ability.
Book-learning comes relatively easy to me, so personally I have had no difficulty getting good marks on the examinations that I have written; but I would have no qualms flying with someone who scraped a bare pass.
"In theory, there is no difference between theory and practice. In practice, there is".