The last time this happened I wrote to the school concerned saying that, even though I had not applied for the post of girls’ PE teacher, and had only written a reference for a candidate, I was now so mortified at the disappointment that my self-esteem would never recover. A few weeks later I received a letter addressed to “Ted Wargg” apologising for the error and blaming a “temp” for the momentary lapse in standards. You just can’t get the staff nowadays.

It all seemed to illustrate the chaos that exists in many establishments, not just schools, as more professions become mobile rather than permanent. Armies of temps, clutching their copious holdalls, now inhabit broadcasting, publishing, teaching, the health service, and numerous other jobs that used to pride themselves on the devotion and calibre of their permanent staff. Some members of the Government relish this crude manifestation of “the market” and want every teacher to negotiate an individual annual contract, which would produce even more armies of carpetbaggers roaming around looking for a post. Any teachers having business cards printed should insert the slogan: “Have chalk, will travel”.

Cuts in education funding, increasing sickness among teachers, individual annual contracts - if they ever come about - will make teaching an increasingly footloose profession. More and more teachers in pursuit of short contracts will find themselves hawking their wares like tinkers around interviewing committees. This will spawn a new breed of itinerant professional - mobile, smart at answering interview questions, well scrubbed and polished. Some itinerants have achieved high office, slipping deftly in and out of jobs just before they were rumbled.

The problem with the shift to more short-term appointments is not just the difficulty of rumbling a charlatan at interview, it is what inevitably goes with the stop-gap approach to teaching or any other profession. First, there is no clear career path. People can go up and down like a roller coaster, soaring to a post of high responsibility one day, being made redundant and having to take any old job to pay the rent the next. Second, much more pressure falls on the so-called permanent staff, as they have to solve the serious problems, deal with parents and the community, plan ahead.

Many people on the short-contract circuit are, of course, excellent teachers, sometimes forced into mobility by circumstances. Women teachers in particular, however brilliant, have often interrupted a successful career and found themselves having to trek round temporary jobs on their return. The down side of short-termism, however, is that solidly virtuous teachers do not necessarily shine in interview, and some successful new-breed itinerants, though clever interviewees, are as hollow beneath the surface as an Easter egg and just as likely to melt when it gets hot.

Having sat in on a few interviews over the years I have seen some of the more stylish tinkers at work. The Smarmpot wins over the interviewing panel with charm, often targeting the opposite sex. Experts manage to avoid plonkingly obvious crudities, such as “may I congratulate you on your superb dress sense” (which, in any case, does not go down too well with a chairman of governors clearly dressed in what looks like a potato sack). The Smarmpot often flatters by agreeing with the questioner, however banal the question (answering “Do you like children?” with “That’s a very important question” rather than “Come off it, sunshine, is the Pope a Catholic?”).

The Assassin stalks the opposition, picking off the rest of the shortlist one by one. I remember one Assassin who had very expressive facial features. In the period before the formal interviews, when the candidates were being shown round and talked to informally, he never actually said in so many words that the ideas being put forward by the others were useless. He just kept raising his eyebrows quizzically and wrinkling his nose, as if their suggestions were outrageously impractical.

The Oracle remains silent and then gives short, intriguing answers. This only works with the right sort of selection committee, but phrases such as “there are certain resonances” or “it depends where you’re coming from” do seem to go down well with some panels. Personally I have always assumed, wrongly perhaps, that if people have anything intelligent to say they will say it, rather than weave a web of Sanskrit around it. However, with some interviewing bodies empty gibberish may succeed. It might be worth practising phrases such as: “The moon never lights a dark valley” or “Give me a child until he is 46 and I will show you the man”.

The Fireball enthuses about every issue that comes up - been there, seen it, done it - sometimes claiming to have direct personal experience of so many initiatives you wonder if he ever did the same thing twice. One Fireball tried to impress on the interviewing committee that she had read every book on every new idea in education and was clearly a much more reflective practitioner than any other applicant. The chairman then asked her to describe one book that had particularly influenced her practice, at which she looked dumbfounded and imploded.

Politicians sometimes justify short-termism, annual contracts, temporary appointments and the market approach, by saying that this is how they themselves have to operate - election candidate one day, MP the next, Minister for Brain Surgery the day after. A fat lot of good that system has done us.