Around six out of 10 queries I deal with on TES’s online behaviour forum stem from weak school structures, and the unfortunate reluctance of some people in positions of responsibility to assist staff with behaviour problems. This is tragic, because without a coherent whole-school approach, discipline vanishes.

The scenario usually revolves around a new (but sometimes old) teacher who has attempted to exert some kind of authority, only to find that the pupil has developed their own ideas about notions of liberty. Off the child huffs, grizzling about their Geneva Convention-guaranteed rights. So the teacher follows the manual and escalates the sanction.

And this is the point at which most of the damage can be done. This is the moment that defines the relationship between teacher and line manager. If the latter supports their staff member, the pupil will realise that the teacher’s authority is octopoid, and reaches into every nook and cranny of the school. They see that as it is said, so too shall it be. But if at this moment the system breaks down and the line manager’s spine slithers out of their cloaca and through the school gates, then the illusion melts, the curtain is drawn and the pupil sees that behind it there is only a fat man with a microphone, sweating.

This is the Rubicon of the relationship between the teacher and the pupil. Is the former backed by a formidable and coherent school structure, or do they stand alone like Nelson on his plinth? Few teachers can exert control over their pupils through personality alone. For most of us, having pupils realise that there will be consequences, punitive or pleasant, to their actions is the most potent weapon we possess. If nothing happens as a result of a teacher’s intervention, then that intervention is reduced to ashes, and nothing will come of nothing, to quote King Lear.

Why do some school leaders fall at this important hurdle? For the same reason as anyone: they are human. Just as some teachers forget to turn up for detentions, or fear to issue them, or seek the easy way out of a challenging class (usually involving DVDs of Mulan or Transformers, in my experience), so too do line managers often cock things up. The thing is, Peter Parker, with great power comes great responsibility, and the higher up you go, the greater the damage or delight your actions and inactions generate.

So here are my tips for line managers:

Avoid being the good cop. A teacher calls on you for help; what they don’t need is for you to offer the pupil a cup of tea and a Danish. It’s very easy to be called upon to deal with a difficult situation and then placate the pupil. This is worse than useless. You don’t need to be a hard-ass - civil and professional is fine - but if the child has just told a teacher to go fuck themselves, then it’s humiliating for you to go, “Oh goodness, what a to-do, let’s all be friends.” That’s a resolution all right; for your benefit. The only person who suffers is the poor teacher who just got called a moron, and now looks like one, too.

Avoid taking the apology and running. Many pupils are keen to commit their offences in public and apologise in private. Worse, they know who they need to apologise to, and when. So it’s cowardice of the most craven kind to watch them grovel a bit and then Yellow-Brick-Road them back to the classroom with a “James has apologised, I think he’s ready to come back in to your lessons, Miss.” No he bloody isn’t.

Back your teachers by default. The old saw about “if you want to lead your team, get behind them” has truth in it. If teachers set a detention or impose a sanction, your first reaction must be to support it; the only alternative is to undermine. The pupils see that the teacher’s judgement isn’t backed by the school, and you condemn them to a hell of mockery and insubordination. So back them, and only decline to do so if serious misjudgement has taken place. But they will be the best judges of bad behaviour as it’s right in front of them.

It is very easy to forget how hard it can be in the classroom, especially if you are an old hand in the school, have a position of authority or a reduced timetable, and are able to follow up any misbehaviour with the luxury of free periods. It is vital that all teachers remember what it’s like to be devoid of the invisible cloak of authority or status. It’s the mistake that many educational rent-a-gobs make from their remote eyries, and it’s a sin when a school leader of any kind does it, from head of department to cluster head.

All that is required for misbehaviour to triumph is for good teachers to do nothing.