Being stranded in a failing inner-city comprehensive can be a powerful aphrodisiac. Who needs Celebrity Love Island when you've got Steamy Staffroom Secrets? St Brian's, like so many schools, is a place where love starts and marriages end, an eternal truth that applies to everyone. Even Les Twigg.
Les, an easy-going fifty-something science teacher, recently traded in his Millets checked shirt and corduroys for a leather biker jacket and boot-leg denims. It's all a rather pathetic but at the same time touching attempt to win the affections of Cynthia Thyme, recently returned from Colombia with a new zest for life. Cynthia, a moribund needlework teacher whose horizons previously stretched no further than her pet terrier's next operation, has reinvented herself as a street-fighting, shoot-from-the-hip people's champion; she is currently recruiting kids for a convoy to the G8 summit.
Others are still haunted by the past mistakes of untamed passion. John Baller, as dedicated to his maths department as he is devoted to his wife Pauline, has never really got over a night of lust with Sandie McSniff a few years back after a heavy session in the 13 Horseshoes. But then Sandie has always taken her duties as a mentor seriously, particularly when her charges are attractive Antipodean supply staff. Her one failure was Mick the Aussie science teacher, who still insists that the mysterious sudden death of his lab rats was connected to his rejection of Sandie's advances.
Then there is Orlando Jones, the head of drama, who like Kevin Costner and Mel Gibson, just can't accept that he is no longer leading-role material.
Orlando's mid-life crisis has spanned three decades and he subsists sexually on a diet of Amsterdam prostitutes and sixth-formers who will do anything to get that part in the Christmas show.
The younger shaggers just get on with it. Tiziana Fausti's antics barely cause a ripple of outrage. When Titz catches a cold, 50 per cent of the male members of staff sneeze. But some rumours still shock. Anna Hatch, head of English and supposedly happily married to an IT specialist, can't explain away her eldest son's shock of red curly hair. In the staffroom he is known as Archie, on account of his startling resemblance to Anna's colleague of the same name.
Into the midst of this public-sector bodice-ripper I have inadvertently thrown my own saga. Harry Thomas, whose key stage 3 Sats results have made him the darling of the LEA, has also grabbed a special place in my heart.
Harry recently reformed his band, A Herd of Wildebeest, and I've become his rock chick, or "groupie" as the Year 10 girls would have it.
And, like Les and Cynthia, John and Sandie, Anna and Archie, we have become public property. Never mind Catherine Zeta-Jones and Michael Douglas, photographers from Hello! are nothing compared to the all-seeing gaze of teenagers. 10C can tell me not only where Harry and I ate on Saturday night but what toppings I had on my pizza.
I don't care, though. My heart's beating a little faster these days, the bags under my eyes are a lot heavier, and I'm behind with my paperwork, but suddenly Monday morning doesn't feel like a chore anymore. In fact, it's the highlight of the week.
Charity Casement is the alter ego of a north London teacher. Next week: Harry's proposal