I attempted a critique of the Blairite project and its application to schools. But sections of the audience believed that, as editor of the New Statesman, I must be an apologist for Blairism. I became aware not so much of heckling but of a low rumbling, from which I could pick out comments such as, “He’s really losing it now.” Later, an apologetic NUT official told me: “That was the Trots.” Perhaps. But I have found that union leaders use this catch-all to excuse any misbehaviour at their meetings.

I was not present when Ruth Kelly addressed the Secondary Heads Association in Brighton, but by all accounts her experience was similar to mine. Open heckling is easy to deal with - a skilful speaker can put the heckler down and isolate him or her from the rest of the audience. But what Ms Kelly seems to have faced - and what I remember facing - is derisory laughter, muttering, groaning, theatrical head-shaking and the odd shout of “No”. In other words, it was much like the low-level disruption that teachers so often complain of in classrooms and which, they say, can be harder to deal with than outright disobedience.

I do not claim to be a great speech-maker. I cannot judge Ms Kelly because I have not yet heard her make a full public address. But if our audiences thought we were bad performers, talking rot, they had every right to express their dissent. After all, I was receiving a fee, presumably paid from NUT subscriptions, and Ms Kelly is employed by taxpayers to make a decent fist of running education.

Even so, my limited observations suggest that what Ms Kelly and I experienced is not unusual, and that among non-teachers (fellow professionals usually get a better reception) we are not the only victims.

I recall Helena Kennedy QC leaving in a fury after talking to a group comprising mostly teachers and ex-teachers about her report in 1998 on further education. Again, the complaint (I think) was about a background of mocking and patronising chatter. I would say that, of all audiences, teachers are by far the worst - the least appreciative as well as the most inclined to start muttering among themselves.

Why is this? I offer several hypotheses. One is revenge: teachers want to give us a taste of what we (or our children) have often inflicted on them.

Another is that teachers are bad listeners: they mentally mark speakers out of 10 and instinctively want to correct them when they’re wrong or expressing themselves badly.

But I incline towards a third hypothesis. Teachers do not like others lecturing them about their work. Schoolteaching is a peculiarly difficult job because almost entirely it involves dealing with people who would rather be somewhere else and doing something different. Police and prison officers are the closest analogies - I am told that they also make difficult audiences - but they enter their careers with full knowledge of their custodial functions and have few ideals to lose. Moreover, society generally acknowledges the challenges they face (“our brave police” and all that). But teaching is widely viewed as a doddle, not least by some newcomers who are soon disillusioned. Teachers do not believe that outsiders can grasp their problems. This is why, for most of the past three decades, politicians have adopted entirely the wrong tone. Teachers want to be coaxed, not bullied. They think they have enough day-to-day problems without other people hectoring them. That low rumble that speakers hear at teachers’ conferences echoes the low, discontented rumble that you will hear in staffrooms up and down the land.

Peter Wilby is editor of the New Statesman