Hurrah, yaroo, jolly hockey-sticks and all that . . . St Trinian’s is back, this Christmas’s anarchic antidote to Harry Potter, and one of the starlets, the fetchingly named Talulah Riley, warns us that she and her fellow celluloid schoolgirls will be doing “anything and everything — there’s drugs, there’s sex, there’s tattoos and piercings”, to which the director adds (perhaps redundantly): “It’s going to shock some people.”

The first rampaging schoolgirl film, The Belles of St Trinian’s, came out in 1954, a year after their creator, the cartoonist and writer Ronald Searle, thought he’d killed his delinquent gels off for ever in an atomic explosion. One of his early cartoons (the first appeared in 1941) showed a Victorian-looking schoolmistress confronting a line-up of pupils with the words: “Hands up the girl who burnt down the East Wing last night.”

Searle’s description of the quintessential St Trinian’s girl is that she should be: “sadistic, cunning, dissolute, crooked, sordid, lacking morals of any sort and capable of any excess. She would also be well-spoken, even well-mannered and polite. Sardonic, witty and very amusing. She would be very good company. In short: typically human and, despite everything, endearing.” This sounds like the perfect description of a journalist but it’s also not all that far removed from some other fraffly well-spoken (but also fraffly naughty) girls that I remember from the class of ’74 at Cheltenham Ladies’ College.

It all started innocently enough. A vast swarm of chattering girls at Paddington station in our greengage scratchy uniforms, satchels, tuckboxes, my mother in mink with a strained expression of jollity, doubtless concealing her mixed feelings about packing off her 13-year-old to boarding school.

I don’t remember that first train journey but the boarding house certainly came as a bit of a shock.

The dormitory with its basic cubicles — a dozen identical boxes painted magnolia, narrow beds with thin candlewick counterpanes in bleached colours, a flimsy strip of fabric at each doorway for privacy. Many years later, when I visited the inmates of Holloway prison for an article, I got a whiff of my old boarding school but the rooms of the female cons, fortunately, resembled undergraduates’ rooms rather than those we had to endure at the (huge) fee-paying CLC.

Like prisoners, we forged our alliances through what we had to offer — our currency was the ability to tell an entertaining story or share unusual but delicious things to eat. That evening I tasted Kendal’s Mint Cake for the first time with my friend from the North.

Downstairs in the communal living-room, the older girls flicked their hair and moaned on sofas about their summer love affairs to Serge Gainsbourg and Jane Birkin’s heavy-panting hit on the record-player — Je t’aime . . . moi non plus — while we read about the horrific butchery of Charles Manson and his followers — some of the girls had attended the American equivalents of our school — in the copies of Paris Match and Life magazine. While the spirit of the Sixties was raging all around us, we were still walking to Col in crocodiles and having institutionalised “pashes” — the female equivalent of fagging in boys’ schools — on older girls.

In the early years, our naughtiness was restricted to midnight feasts and breaking (sometimes unwittingly ) a myriad of tiny rules. Eating currant buns in a public place while in CLC uniform was a major transgression. Talking in the black and white tiled marble corridor on the way to morning assembly was a no-no. Pretty soon, I was part of a gang of four girls who were always in trouble for minor infringements and we were constantly hauled in front of the headmistress, Margaret Hampshire, known as Hammy.

Miss Hampshire, unbeknownst to us then, was a bit of a rebel herself and certainly a modernist. A civil servant turned industrialist — from 1959 to 1964 she was head of the government relations department at Courtaulds — her appointment at CLC in 1964 was controversial (she remains the only head in the school’s 150-odd years history to come from industry) prompting one retired head to write to the education minister in protest.

During her tenure (1964-1979), which coincided with my years at Chelt, she built a new wing for the sixth-formers, started a school forum and introduced joint lessons in the sixth form with boys from Cheltenham College. (Old boy Lindsay Anderson made his version of St Trinian’s in his explosive film If.)

In those early St Trinian’s films, the schoolgirls were either lower-fourth hoodlums using their lacrosse and hockey sticks as lethal weapons and doing dreadful things to their teachers, or gin-swigging, cigar-puffing harlots, hitched-up skirts revealing black stocking tops, with unspeakable morals. Those of us who had good legs also went in for multiple waistband-rolling, cunningly letting the olive worsted down for episodic skirt inspections. Others of us customised our sweaters by scissoring the cuffs so they unravelled in boho dissaray.

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