Some interviewees are naturals - they're articulate and can express themselves well, often with little preparation.
Then there are others who prepare to the nth degree but somehow can't communicate it well in their personality - nevertheless, they are good people. It's important that you take this into account when putting interviewing structures into place.
I remember when I was appointed to the deputy headship of a large comprehensive in Essex. There were six candidates and, having a name beginning with W, I was last in. I wasn't interviewed until about 9pm and, as I'd been there since 8am, I was exhausted.
Before the interview, we were in an anteroom, being plied with sherry and cake by one of the secretaries. As I went in for the interview, I tripped on the stairs and fell flat on my face - probably the sherry's influence - and was then presented with about 35 people on the governing body.
Because I was relaxed and thought I had no chance, I interviewed well - and I got the job. Despite that, it showed me that this is not how to do it. You don't put people through the mill over the course of a whole day. You don't have them in for an interview at 9pm; you need to think carefully about structure.
At another interview for a head of year position, I had prepared well. Because it was a pastoral position, I'd read all the books on pastoral care, and I went into the interview and quoted chapter and verse. They had heard of a lot of the principles I'd read about, but that was not what they wanted to hear. They were more interested in how I would do the job, and what sort of personality I had, which didn't come across because it was clouded in all sorts of theoretical discussion.
At our school, if candidates are coming for a main scale job, we make sure they're welcomed - not by myself or a deputy head, but by somebody within the department they are being interviewed for. They're taken to the staffroom, given coffee, introduced to staff, who talk to them about the school's cultural ethos. Their first hour is one where they're not intimidated by the top brass giving them a semi-formal interview.
When they tour the school, they are gradually introduced to more senior people. Eventually, when they see me, they're well prepared and it's not an intimidating experience. And we don't give them sherry.
Sir Michael Wilshaw is head of St Bonaventure's school, London borough of Newham. Interview by Martin Whittaker