At the end of my PGCE course I didn’t get a permanent job. Instead, I put my name on my local authority’s supply teaching list. What a huge shock the first couple of weeks were. How naive and innocent I was. After all, there had to have been some reason why their normal teacher wasn’t there. As soon as I walked into the classroom I realised what it was. I was minding 3C, the class in the Anadin advert, and Mrs Jenkins was in London having psycho-therapy.

My PGCE course was quite good as preparation for a permanent teaching post. I had experience of all the things you need to be a full-time teacher. How to plan a lesson. How to prepare a scheme of work. How to touch all the bases on the key stage 3 syllabus, how to make the head of department look good. Supply teaching is a different job. I have had to learn it by trial and error. For those who end up in the same situation as myself here are a few do’s and don’ts.

A supply teacher suddenly finds himherself in nominal charge of a class of total strangers. They’ll try it on, simply because they think they’ll never see you again. You need something to scare the pants off them. In ascending order of value : * A northern or Scottish accent. In the Home Counties they think us northerners are hard. We frighten them. An Ulster accent used to be even better but the peace initiative has put paid to that . . .

* A lobster red Benidorm suntan; useful because it makes you look apoplectic with rage.

* A facial twitch. Inspector Clouseau’s boss (Herbert Lom) in the Pink Panther films had one of these. If used effectively it can give you that “about to start wielding an axe” look that most children still respect.

* A duelling scar. German specialists might think about acquiring one on their next visit to Heidelberg. A livid purple gash from eye socket to cheekbone can be amazingly effective on a Friday afternoon. On the other hand, an eye patch or a hook are not to be recommended. You need all your senses in full working order.

* Unless you are a genius you will not succeed in learning the names of all the children in a single lesson. In a crisis, however, it is always worth having a guess. Shane, Wayne and Lee are a good stab if the boys at the back are fighting with knives; Kylie and Sharon if one of the girls is about to become pregnant under a desk.

Remember, you need to nurture your aggression before you go over the top, so avoid anything that releases stress, such as: * I once made a trip to the bottle bank before an afternoon class. Big mistake, hurling the bottles into the container - that sound of smashing glass is just the sort of soothing, tension-reducing activity to be most avoided. On your way to work it is worth setting off late and seeking out the biggest traffic jams. Gangster rap records for the car cassette-player are also good.

* Don’t throw away those Eighties suits. Power-dressing may be dead elsewhere but it is still alive in the classroom. You can’t be a caring Nineties person and a supply teacher.

* Don’t feel compelled to tell the truth. A good lie - “He’s called that because Harper Lee was a big fan of the Boo Radleys” - can be much more effective than the truth as motivation.

* Don’t leave yourself without an excuse if things go wrong. If another member of staff comes in and sees chaos, you will never work there again.

Have a suitable explanation lined up, whether it be science: “No, the pellets and paper planes are for an aerodynamics experiment”; history: “We’re re-enacting the battle of Agincourt”; art: “We’re doing a tableau vivante based on ‘The Wreck of the Hesperus’”; or English: “They’re exploring their inner rage like King Lear.”

Nicholas Hill is currently working as a supply teacher in North Yorkshire