Nigel Horsmel’s seizure of power at St Brian’s has met unexpected resistance. The acting head has swept all before him since the head went into rehab last term - but the fightback has begun.

Horsmel easily crushed the pockets of opposition among the governors and senior management team, but his blitzkrieg missed one important target: the school office.

It has taken me most of my NQT year to realise that the real power broker at St Brian’s, the political puppet master, is Miranda the receptionist, or “M” as she likes to be known. Like all members of the admin staff, Miranda doesn’t have a surname. At first I mistook this for snobbery - middle-class professionals deeming mere office workers to be undeserving of a respectful form of address - but then I realised that it was a deliberate desire for anonymity on the part of “the girls”. Anyone foolish enough to ask for more detail just gets a sweet smile and a curt “Oh, just call me MirandaRachel Sandra - everyone else does.”

As I stroll into the office, tranquil as ever, the air heavy with pollen, I see Miranda sitting regally in her swivel chair, staring at her computer screen. “Hard at it, M?” I say with a smile. “Eh? Oh yes, just trying to decide whether to go for the organic kiwi fruit this week. Five for two quid. What do you think?” I look over her shoulder and see that Miranda is completing her online grocery order.

There’s a female squeal and I turn to see Amy Studds, the bursar, holding up a lacy negligee. “What do you think?” she pouts. The girls have just taken delivery of the latest Ann Summers collection, ahead of their monthly sex-aid party tonight. Amy, pitiless enforcer of the ancien regime, has reinvented herself as giggly woman of the people since falling out of favour with the new order.

The office is a different world. The staff drink percolated coffee, not instant, and they discuss normal topics like shopping and sex toys. But, like every successful resistance movement, the veneer of normality is but a front for a ruthless fighting machine.

Miranda never challenges Horsmel directly, relying instead upon her network of guerrillas to undermine him at every turn. So when he arrives for lunch there’s only one piece of stale cheese pie left, deposited on his tray by Dionne the kitchen manager with all the grace and charm of Gordon Ramsay.

Rose the cleaner, a popular, garrulous type, becomes an accident-prone mute upon entering his office.

The staff car park is another danger zone for the acting head. Roy Striper, the caretaker, pleaded ignorance after the incident with the refuse truck, saying only that if people will insist on parking their cars so close to the bins then these accidents will happen. And the photocopying room is a complete no-go area. Horsmel can expect worksheets to be illegible or blank; that’s if they don’t disappear altogether.

Take on Miranda and you take on the underbelly of the school. Nigel Horsmel has yet to understand this. But I accept allies wherever I find them. As I get up to leave the office, I pat my heaving shoulder bag and turn to Miranda, still poring over her Waitrose order. “It’s all go, M, but I think I’m winning.” She looks up and winks. “Oh, yes, Charity, we’re winning all right.”

Next week: Tiziana takes a trip