I don't usually go out during the week. Ever since I was installed as temporary head of history, I've taken to going to bed at 9pm. So a couple of halves in the Horseshoes on a Friday evening is about my limit these days. I'm 23 years old.
But I'm making an exception tonight. Blaine Harrington, my line manager, has invited me round to his flat to help me out with my pupil tracking data. I like Blaine, and even though he's gay I find him exciting, sexy even. It's fun to flirt with a bloke who you know won't get the wrong idea.
So tonight it's a bottle of Chablis, a Thai stir-fry and some unthreatening male company for me.
At 7pm I find myself standing outside a gated complex of loft apartments gazing at the rows of shiny Mercs and Audis in the car park. I wonder how a teacher can afford to live in accommodation normally reserved for solicitors and stockbrokers, but then I remember that Blaine isn't like me; he's an advanced skills maths teacher.
A burly porter is refusing to let me in until Blaine's gentle voice wafts across the intercom. "It's OK Harry, she's one of mine," he says and the gate swings open. The flat is a seamless open-planned expanse of cherrywood and glass. Blaine gives me a peck and then stands back to study my outfit, nodding appreciatively. He ought to like it; after all, he chose it for me when I got my promotion and we went to Harvey Nicks to celebrate.
He skips off to fetch an aperitif, and I perch on a huge slab of slate which I assume is for sitting on. I watch Blaine's blurred outline through the glass brick wall and get that tingly feeling again. I flick through the DVD collection. Nothing too controversial: a Judy Garland box set, some Bronski Beat videos, a home-burnt disc with "River Phoenix stuff" scribbled on the cover. Then, puzzlingly, Arsenal: best of the Gunners 2004-05.
While I'm still trying to interpret my strange find, Blaine arrives with two champagne cocktails. The conversation swiftly turns to the exotic smell coming from the kitchen, which apparently is a recipe he picked up on his last trip to Morocco.
I open my laptop. "What's that?" Blaine asks, sounding disappointed.
"It's my tracking data. That's what we're doing tonight, isn't it?"
He smiles. "It's ok, Charity. I've read it, it's fine," he says, as he strokes my forearm.
"Well we could just watch a DVD if you prefer," I mumble.
"Let me show you what I would prefer," he whispers, leaning over and snapping the laptop shut. A mixture of panic and excitement wells within me.
"Charity," he whispers, an intense look in his eyes as he attempts to kiss me. I jump up screeching. "Are you mad? You're supposed to be gay! Or at the very least bisexual!"
"Oh come on, you must have heard of metrosexuals. Just because I smell nice doesn't mean I don't like a bit of girl action."
I breathe deeply and walk to the door. "Right, I'm leaving now. But let's get something straight. You don't get to tell me how to run my department any more, and from now on I do my own shopping. In fact, you don't get to tell me anything because I'm not taking that crap from a... from a heterosexual man!" I slam the door and burst into tears.
Charity Casement is the alter ego of a north London secondary school teacher. Next week: Best practice, St Brian's style