I was applying for teaching posts well within my capabilities, and alerted the head prior to each application; but I was not shortlisted. I suspected that the head was not being as supportive as he might have been, but I was unable to obtain a copy of his references.
My union advised me to request an open testimonial from the head, which I did. The testimonial was extremely supportive, and I was successful in my next application. The reasoning behind the union's advice was that a school will inevitably require a reference from your present school's head and that it would be difficult for a head to express reservations about an applicant about whom he has already written a glowing testimonial.
In an ideal world there should be mutual professional trust between applicant and referee; and in my experience most heads are supportive of a teacher who applies for a position to further his or her career.
However, I believe that the teacher who asked Archimedes about reference confidentiality was concerned about the possibility of a head providing a bland, or even negative reference, for the sake of retaining a competent teacher for a few more months. Perhaps it is this matter that Archimedes should have addressed.
Michael Derry Willow Cottage 6 Gonerby Lane Allington Grantham, Lincolnshire