The majority of deputies work their socks off with very little appreciation from their heads, colleagues, parents or the local authority. It is expected that deputies will be at everybody’s beck and call, drop everything for whoever, have no agenda of their own and be a constant source of soothing balm, encouragement, inspiration and energy.

Unsurprisingly, more deputies burn out than either heads or classroom teachers, despite the well-documented concern about both these other groups. Deputies are the silent minority, the forgotten troops in the education army, suffering the most casualties, providing the most support and receiving none of the glory. It does not have to be this way.

Like teachers in general, deputies are their own worst enemies. Somehow a message went out that deputies should be downtrodden, taken advantage of and generally exploited. For the most part, we dutifully line up to take it again and again. Rather like Charlie Brown running up to kick the football, only to fall flat on his back as it is whisked away from beneath his feet, so deputies scurry about for everybody else every minute of the day, totally exhausting themselves, only to find they are on the receiving end of carping and criticism.

The solution is to be very clear in your own mind what you are actually about. Deputies too easily become prey to other people’s expectations. They feel guilty about being paid more than their colleagues and overcompensate by driving themselves into the ground. A purposeful approach, unswayed by circumstance, often yields better results. Work out your priorities and stick to them. By all means accommodate tasks that are relevant or further your goals, but do not become distracted by irrelevancies. As there are so few people in education with any defined purpose, it is always refreshing to come across somebody who is clear in their aims and is setting about achieving them.

Good deputies will be able to reel off their three key objectives for the school and relate how they are going about implementing them. Everything else is incidental.

Some people will be recoiling in horror at this point as their ideals are challenged. Surely the deputy’s role is to support colleagues, provide a model of excellent practice, loyally carry out the head’s wishes? Is not a deputy with his or her own agenda a very dangerous commodity in a school, a destabilising influence? Far from it.

A deputy who tries to be all things to all people achieves nothing for anyone, becomes tired and despondent. On the other hand, a deputy who is focused to do a few things well for a few people benefits all in time. When I first became a deputy head, my three objectives were to build a junior staff team, change the maths scheme and get a microwave for the staffroom. I may have supported colleagues in the process, I may have carried out the head’s wishes (though not over that microwave). I was certainly not a model of excellent classroom practice, far from it. But I fulfilled my objectives.

As each was achieved, new targets came on to the agenda: to win admission appeals, to replace mobiles with permanent buildings, to enforce the wearing of school uniform, to extend the school day and so on. My energies went first and foremost into the key objectives of the time. Everything else had to take its turn. My objectives tended to be school-wide, though some of them were more junior-based. I did not allow other things to distract me and I encouraged colleagues to undertake those tasks I could have done myself but preferred not to.

Usually the whole school benefited from my achieving an objective. When we started to win appeals, class sizes stabilised. The new maths scheme was welcomed throughout the school. Everybody enjoyed the use of the microwave. People prefer a deputy to get one small thing right, than to see a multitude of things go awry.

To stay sane and be appreciated in equal measure, you need to have no more than three priorities on the go at any one time. Stay focused: do not become distracted by anyone. Articulate your priorities clearly and widely and tell people how they will benefit. Then tell them when you have achieved your objective. And never give up: if it’s worth fighting for, it’s worth winning.

When deputies are first appointed they are apt to dream a little. Yes. you would be that excellent classroom practitioner sought after in the selection criteria. Yes, you would be that confidante to your grateful colleagues and that wise sounding-board to your head. Curriculum co-ordinator? No problem. Named person for whole-school assessment? A doddle. Within months you will have made such a difference to the school that everybody will be wondering how they ever coped before you came along. Reality comes as something of a surprise.

In many ways your fate was sealed before you even started. The over-riding measure against which you will be judged - certainly in the first year - will be the standards set by your predecessor. If this person was universally loathed, an idle good-for-nothing waster, then simply by saying “Hello” you will be an enormous success. If, on the other hand, your predecessor was a cross between Superman and Mother Teresa (and we’ve all met them on courses) your highly impressive curriculum map will pale into insignificance compared with SuperTess’s coffee washing-up rota, which is still in use.

Your first task, therefore, must be to assert your individuality. Do something, anything that your predecessor didn’t think of. It doesn’t have to be spectacular, in fact something small scale would be less of a threat to colleagues.

Remember they will have taken a great, if detached. interest in your appointment. The caretaker probably ran a sweepstake while you were being interviewed and the secretary may have gone round briefing teachers about how you were doing. Your colleagues all have a share in you, as if you were a racehorse they had clubbed together to buy. They want you to succeed, but they will be monitoring your form closely.

The first thing I did was to take Monday morning assemblies and give my colleagues free (sorry, non-contact) time. Previously they had taken it in turns to do the assembly and the deputy had drawn up the rota. As colleagues considered this change beneficial, I was able to store up a small fund of goodwill.

You will find that you will be expected to maintain all the things your predecessor did, unless you can prove that they are pointless or plain daft. Some of the duties I inherited were taking the minutes of staff meetings, collecting for the school’s 200 club among colleagues and changing the class dinner rota every half-term. Any job that the head does not want to do tends to trickle down to the deputy and any jobs the staff do not want to do are pushed in your direction as well.

At the first sign of hesitation, the first hint that it is not unadulterated joy for you to conduct the daily inspection of the boys’ toilets or run the thrice-weekly pupil-consultative steering group, somebody is bound to come out with the well-honed phrase: “But the deputy always does that.” Be ready for it. It is more likely to be spoken in its most naked form by a dinner lady, ever conscious of rank. Your colleagues and especially your head are liable to be more subtle: “Sally was always so keen to chair the parents’ association and willing to give up so many of her weekends to prepare for the school fete. I’m sure your sentiments are entirely similar.”

You will end up cursing your predecessors. If they were useless, you will face a suspicious and demoralised staff, expecting more of the same; if they were wonderful, you will never match their superb record and somebody is bound to make an unfavourable comparison. They will have agreed to do the most meaningless and menial tasks, which you will now be saddled with, unless you learn to say No.

So learn to say No straight away. Say No to the head. Say No to your colleagues and say No to the dinner lady. Remember, the more you say it, the easier it gets.

* Nick Butt is head of St Edmund’s Community School, King’s Lynn, Norfolk, and author of The Deputy Head’s Survival Guide (First and Best in Education Ltd; Pounds 12.95).