One of our parents summed up that investment painfully clearly when she said: "I have come to the conclusion that everything depends on the quality of the teacher." But if she is right, commitment of time and energy is not of itself enough: the process must work.
Interestingly, research on recruitment methods puts work sampling much higher in effectiveness than interviewing. That gives us some measure of reassurance since, for the past eight years, we have asked candidates to teach and be observed on the day of interview.
Before that, we had always invited them for the whole day but too often we sat in the formal interview in the afternoon trying to imagine them with a class of children. It seemed fairer to them - and to the school - to do away with guesswork and ask them to teach.
Now, when the letters go out inviting candidates to interview, we include the information that they will be required to teach. Typically, the day will begin with an introduction to the school from the headteacher, a tour of the school and an opportunity to meet the department staff. Then comes the teaching.
Candidates are sent details of the number and ability levels of the pupils they will work with, and the course they are following. Usually candidates are given a topic, although this may be more or less closely defined according to the subject. They teach one 50-minute lesson and, to make comparison fairer, we try to ensure that all candidates for the same post teach classes in the same year group.
We tell them that we are not looking for the best lesson but for the way they relate to children, their style of teaching and ability to motivate pupils. A rota ensures that all interviewers, including the governor involved and the relevant head of department, observe each candidate. This usually means an observation team of four.
Observers may work singly or in pairs, each watching half or a third of a lesson. At the end of the process they sit down and compare notes. Between everyone, the whole of a candidate's teaching lesson will have been watched and commented on.
Our pupils are welcoming to these "visiting teachers" and have come to understand and respect what is going on. At first we were reluctant to invite their responses, but as the process has developed, we have become more and more interested in what they think. They take some care and pride in forming their opinions and, when asked, often show great insight, discretion and maturity in offering their views to the official observers.
At the end of this part of the process, we often feel quite certain that some of the candidates are definitely more appropriate for our school than others. Yet, until recently, we still persisted in putting them all through the formal interview.
So we have introduced another change - reducing the interview list half way through the day. This has become common in headship and senior staff interviews but we had been slow to apply it to the appointment of less senior staff.
We began to include in the invitation letter the statement that there would be a decision at lunchtime as to which candidates would be invited to remain for the formal interviews in the afternoon. We agreed we would introduce this if the interview panel was unanimous about a cut - and here another factor has come increasingly into play.
Although we involve many staff in the process during the day, we have a group of staff and a few governors from which the core of the interview panel is always formed. This core is becoming used to working together, so we find we are reaching a consensus more easily - this includes regularly agreeing to reduce the list at the end of the morning. It is hard to disappoint candidates at any stage of the day, but probably more honest to do it at that point than to interview people we know we will not appoint.
Having reached the end of the formal interviews, we have also abandoned the nail-biting pressure of all candidates waiting around after their interviews, often into the twilight of an emptying school. That was hard on everyone, both candidate and interview panel which felt under pressure to deliver its verdict in a time scale which did not always allow for consideration and reflection. Now candidates are told they will be free to go after their interviews and that they will be notified as soon as possible, either by letter or telephone, which we try to do within 48 hours.
These changes have undoubtedly improved our selection process. The design of the interview day and the inclusion of teaching gives us more of the kind of information we need and the scope to make a good decision in the best interests of our school and, we hope, of the candidates.
Rosalie Clayton is principal of Comberton Village College, Cambridge