Monday morning, 8.30, and Jamie is waiting for me at the classroom door.

“Morning, Miss. The place was in a right state, so me and Dan gave it a good Hooverin’ yesterday afternoon. Oh, and I watered your plants. Want me to go and get the other lads in?”

As my students are being rounded up by Jamie, Martin sticks his head round the door. “Now then Tab, d’you want me to get you a coffee before you get started?”

Welcome to the grim reality of prison education. My domain is a small, well-lit basic skills classroom on a wing where about 100 prisoners are tackling their long-term drug abuse through group work, peer support and a vaguely evangelical daily meeting. “Therapeutic community” is the technical term, although the “Happy Clapper Wing” is its more usual title around the rest of the prison.

Whatever you want to call it, it’s a bold attempt to tackle a problem that most of society views as insurmountable, and I love my job so much that I’d probably do it for free, which is the main reason I’m writing under a pseudonym - my boss reads this paper.

A few people have muttered that I’m mad (mainly the ones who’ve watched Midnight Express too many times). You must be kidding. “On the out”, I taught feral 15-year-olds who ran their illicit ciggie shop from the back of the classroom as I vainly tried to deliver a doomed citizenship lesson, and 11-year-olds who would jump onto the bonnet and roof of my car as I drove from the car park. Urban Longleat or HMP? No contest.

When you start at the prison, there are lessons you learn quickly. Such as, ironically, the fact that prisoners are the most honest students you’ll ever teach. Brutally honest. Take Michael, for example. “If you don’t mind me saying so, Miss, you haven’t dressed to your usual high standards this morning. In fact you look like you’ve been hauled through a hedge backwards.” Well thank you very much, Monsieur Gaultier.

Also, things can take on an entirely different context this side of the wall. A maths book asks: “If one screw weighs 10 grams, how much do 20 weigh?” On the out, it’s a perfectly sensible hardware question.

In here, you get: “Blimey, Miss, d’you reckon he was on the Atkins Diet?”

Actually, “blimey” wasn’t the exact expression, but this is a respectable publication. As fantastic as my job is, it’s perhaps not the best one for someone fresh from the convent.

But it’s not all fairy tales. There’s the usual FE hassle: unreachable targets, Himalayan piles of paperwork, not enough hours in not enough days.

And then there are the added challenges of working behind bars.

It’s a parallel universe. My very best students - the ones who live at their desks and have a work ethic that puts me to shame - are the ones I fervently hope I’ll never see in my classroom again.

The lads who leave me gibbering for the Prozac are the ones I can guarantee will be with me from beginner reader to PhD, probably over the course of half a dozen sentences. And have you tried working in a classroom where Blu Tac and scissors are banned?

Fortunately there are too many good bits to choose from. Where do I start? When the smack loses its grip and the lights come back on behind the eyes and Steve gleefully informs me that he’s put on half a stone in a month.

When Mark puts the finishing touches to his university application. When Dave, a 50-year-old who looks about 93, tells me that once he’s out, he’ll finally be able to help his kids with their homework.

When Kevin confidently answers the daily quiz question “What’s the biggest mammal in Britain?” with “A big dog”, and I laugh so hard my coffee comes down my nose.

Like I said, I love this job. I think insanity may run in my family, as my three-year-old daughter has recently told me she wants to teach in a prison when she’s a big girl. Not sums, though: “Mummy, I’ll come in and teach the men how to fly aeroplanes.” They’d love that.

Tabitha McGowan is a pseudonym