Ordering teachers to take an "MoT" will not root out the dross. Photo: GETTY

After two decades in teaching, I've realised that the really hapless members of my profession can be divided up into three distinct categories: the weirdos, the breakdowns, and the brown-nosers.

The weirdos are the easiest to spot. We've all been taught by at least one. The highlights from my own career include the teacher searching for inner peace, who liked to sit cross-legged under his desk, issuing his instructions sotto voce as his classes rioted; the obsessive compulsive who spent most of his lessons making sure that the children, desks and everything else were in a straight line; and the hypochondriac who felt his noisy classes were making him deaf and so wore noise-cancelling headphones for much of the lesson.

Then there were those who, for various reasons, just could not communicate properly: teachers with English as a 20th language, teachers with no teeth, teachers with chronic adenoids, teachers with alcohol and drug problems, teachers who only whispered, teachers who only screeched, teachers with such bad body odour that no one dared venture near them.

The breakdowns tend to be a different species. These are often good men and women who have been sapped of the will to teach. I have to confess that during the mid-1990s, I was one myself: a burnt-out, exhausted soul who had been ground down by chronic indiscipline, unsupportive colleagues and insane bureaucracy. I actually sacked myself, leaving the profession for a few years to do other things before returning with my confidence restored.

The brown-nosers, however, are rarely unearthed. These are the teachers who sound wonderfully plausible, spouting jargon and sprouting paperwork. But they are, in fact, inept. Take the support teacher who absented herself from most of her lessons until Ofsted appeared, when she sucked up to them so beautifully that she earned a promotion.

Even the General Teaching Council for England (GTCE), the professional body usually anxious to present its members in the best light, has admitted that there are at least 24,000 incompetent teachers.

Hence the Government's latest brainwave: to insist that we apply for a licence every five years. I had visions of striding into the classroom like James Bond, and pointing my whiteboard pen at the pupils as if it were a Walther PPK. "Don't mess with me, kids, I've got a licence to teach!"

Ed Balls, the Schools Secretary, thinks he's really going to make a mark upon the educational landscape with this idea. But having spent my entire career in state-sector secondary schools, I know that ordering teachers to take an "MoT" will not root out the dross. The Government has already brought in "competency proceedings" designed to give headteachers the power to show rotten staff the door, but since the GTCE took overall responsibility for firing state-sector teachers in June 2001, only 10 have been barred for incompetence.

Mr Balls's new plan will not change the situation: a fatal combination of powerful unions, institutional inertia and mind-bogglingly complex legislation means that cutting out deadwood will always be fiendishly difficult.

In fact, I bet the brown-nosers will love the idea of introducing teachers' licences: they'll thrive on the paperwork and back-covering. But most good teachers know that the idea is asinine. The only people who need their licence revoked are the jokers running our schools.

Francis Gilbert is the author of 'Parent Power – The Complete Guide To Getting The Best Education For Your Child' (Piatkus)