One in five union representatives in schools has never raised members'
issues with the management, according to the study by Howard Stevenson of Leicester university. And of these, a quarter would have to undergo a period of introspection in order to do so - because the head and union rep are actually the same person.
The study found that where union reps adopted a more proactive role they could have a "significant" impact on schools. It also suggests that union reps are more likely to pop into the headteacher's office for a quiet chat than take on the management in meetings.
Although new issues such as redundancies are encouraging union reps to adopt a more high-profile position, most avoid becoming involved in disputes over redundancies at their school, preferring instead to defer to the local union officer.
Some reps do not make any attempt to mobilise members even when a fellow member at the school is threatened with redundancy, the research says.
One union rep at a primary school told researchers: "I did it because nobody else would do it. Originally, I saw my role as opening the envelopes - making sure that everybody got everything they were supposed to get.
"Just recently it's changed a bit and I have felt out of my depth. Things have gone on at school where I have actually had to go to management and present the union's position. I have found that very difficult - the past couple of terms have been awful."
Reps in primary schools are less likely than their secondary counterparts to take an active role in school, the study found.
The research is based on questionnaires sent to representatives of the National Union of Teachers in three Midlands education authorities.
It also found that large numbers of union members have no formal contact with the national body through their local association.
A spokeswoman for the NUT said: "The way school reps operate depends on the individual.
"This research is a measure of the good relationships that exist in the vast majority of schools."