The system of appointment bears very little relation to how good a teacher a candidate may be. You get an interview based on how well you write a letter, and a job based on how well you answer theoretical questions at the interview, which often depends on whether you have "gelled" with the head or head of department. This does not accurately reflect a person's ability in the classroom.
Why aren't more candidates asked to teach for half an hour? I can appreciate that organisationally this is difficult and may favour "performers" rather than those who build effective relationships with their classes. Alternatively, it would take very little extra effort and organisation to ask each candidate on the day of the interview to plan a lesson on a given topic, then base the interview around this, thus discussing the way that person plans, their use of resources, etc, giving a better insight into them as a teacher, which can only be good for the school.
Teaching is a profession, yet it uses a non-practical test to appoint someone to a practical job. It's time for schools to wake up and be more imaginative in their selection processes. In the long run, it is they who will benefit.
ALISON PHILLIPS 26 Dunsmuir Grove Gateshead, Tyne and Wear