I know about staffroom etiquette, because when I was training I bought a guide that gave tips such as don't use other people's mugs or steal their chairs. So I skulk in the corner, until a man who looks slightly younger than my father introduces himself in a strong northern accent. His name is John Baller, head of maths and the union representative. Five minutes later I have joined the union and agreed to go on strike next month. We're being overworked, undervalued and undermined, John says.
But it's my second day and I haven't actually done any work yet. This morning it's an all-staff meeting with the head, or "Superman" as John calls him. He arrived last Easter to turn St Brian's round and is a star turn at Carole Caplin's dinner parties.
A tall, grey-haired man stands at the front of the hall. "Good morning everyone," he begins. "For the benefit of the newcomers, my name is Dr Alastair Scarlett." Silence. "Please don't ask me about your ailments, because I'm not that kind of doctor." Someone coughs.
While Dr Scarlett talks, a striking woman in a black and red suit with a plunging neckline and very high, pointy black shoes gives a Power Point presentation on a huge projector screen. I later discover that this is Amy Studds, the school bursar. She looks and sounds terrifying. The screenis filled with graphs and diagrams as Dr Scarlett explains about residuals, value added, best practice, Sims, Yellis, Panda, and lots of other stuff.
A group of young women start giggling loudly. Two of them seem to be playing paper-scissors-stone under the desk. I nudge John and he smiles.
"They're Kiwis. Utterly fearless. They know they'll be out in a couple of terms so they don't give a monkey's."
Ms Studds points at a particularly baffling graph. "What does it mean?" I whisper to John. "It means we're crap," he says a little too loudly. "See all those dots on the right? They're our kids and our departments and they're all on the wrong side of the line - in other words, the bottom of the league table. And it's our fault."
John and the Kiwis go to the pub for lunch. I decline because I've got my first class this afternoon: 9C.
I decide to play safe with the lesson plan: a lively, involving discussion on the theme, "What is history?" My college tutors said it never fails.
They've obviously never met 9C. Nor had I.
Nobody told me there were special rules for this lot: no discussions, closed reading assignments, seating plans, and threats of visits to the deputy head's office are the preferred method. Ofsted's three-part lesson certainly isn't an option.
"So what is history?" I ask, waving my arms around in an isn't-this-great-we're-going-to-learn-so-much-together kind of way.
An incredulous silence is followed by a shout of: "It's like Robin Hood: men in tights, innit, Miss!"
Somehow we stagger chaotically from Mel Brooks to medievalism with a brief stop-off for a chat about transvestism. It hasn't gone to plan, but I don't cry.
I bump into John Baller in the corridor. "Coming to the pub, Charity?" he asks. Yes, I think I will.
Next week: In vino veritas