For the past four years, I have been writing a novel about two schools that form an unlikely partnership: one a rich, wildly successful boarding school, the other a fast failing urban comprehensive.

As my husband and I and our two children had all attended private secondary schools, I was familiar with independents. But the heroine of Wicked! A Tale of Two Schools is battling to save her comprehensive, so I needed to research the state sector, and in particular state school heads. And what an inspiring bunch I found them. I was constantly bowled over by their compassion, their courage, and their humour, and appalled by their vast workload, lack of resources and the stranglehold of red tape against which they struggle.

I also sought the inside view on teaching from Sarah Bayliss, editor of TES Friday magazine, who with her tousled red curls and sweet freckled face is pretty enough for any fictional heroine. She confirmed that teachers were indeed utterly exhausted by workload and, because they often married or lived with other teachers, the domestic tiredness levels were doubled - not the ideal material for a bonkbuster. A typical teacher date is evidently being taken to the new James Bond film, and sleeping right through it.

Battling on, I took out a subscription to The TES, whose journalists provide enough good stories each week to furnish a hundred novels, and found my heroine in a marvellous piece by Wendy Wallace. This featured a brave and beautiful deputy head called Katherine Eckersley who, when her school in Derby was closed down, managed to chivvy the local authority into giving her a building and funding to “save” Year 10, who would otherwise have been uprooted and transferred to other schools to take their GCSEs. It seemed to me that a miracle had happened.

All the older teachers at the Village community high school, who’d been demoralised trying to control large, unruly classes, came back two or three days a week and, as Mrs Eckersley’s “Golden Oldies”, taught these 60 children in small classes. The teachers were free to teach and the children, previously regarded as no-hopers, were able to learn and have attention and love lavished upon them. The result was a happy school.

On other occasions I was appalled by the brutality with which schools are closed down. Virginia Frayer, the marvellous former head of the Angel primary school, in the London borough of Islington, misread the privately controlled LEA’s request to visit her thriving and successful school, hoping she would have a chance to ask for more funding. When told the real reason, she gasped: “But you haven’t seen over my school; we’ve all spent weeks making it beautiful.”

Back came the deadly reply: “I don’t need to see over a school to close it down.”

I only hope the designer flats built on the site of the Angel, are ever more haunted by the weeping of children.

I also detested the way schools that close have to endure the humiliation of other schools descending like vultures to appropriate desks, books, computers and lab equipment, though I rejoiced in the story of the enterprising school that flogged off the girls’ uniforms to the local sex shop.

In other schools I encountered extraordinary poverty. Tactlessly teasing an enchanting little girl for wearing a long-sleeved winter shirt in the summer, I was hissed at by the head that her family couldn’t afford two shirts.

Then there was Danijella, the asylum seeker who was put in charge of the school bird table. She was discovered tipping bird seed, stale cake, discarded fat and broken biscuits into her school bag to augment her family’ s rations at the holding centre.

I was frequently moved to tears by the heroism of pupils who are determined to get an education in the face of daunting odds. One child was single-handedly looking after three younger sisters, as her mother lay in a drugged stupor on the living room floor.

Such children face a wall of indifference and cruelty beyond the school gates: no food in a freezing cold house, drunken parents waiting to knock them about, or worse. But they love their parents and won’t sneak because they’re so terrified of being taken into care.

One of the heroes in Wicked! is Paris, who has been in care since he was two, and who regularly goes missing as he travels the country, searching for his mother. I was overjoyed to see The TES mount its Time to Care campaign to improve the lot of looked-after children, who at 17 are so often cast out into the world to drift into crime or homelessness.

I know it costs a fortune to keep a child in care - far more than to send them to Eton or Harrow - and children like Paris only get pound;10 a month clothes allowance, so someone somewhere is doing nicely out of the arrangement.

I was horrified too by the vulnerability of teachers who are accused of abuse: arrested, named and shamed, allowed no contact with anyone from the school, until a court case comes up, often months later, their lives, too, are truly blighted.

My husband claims he can only play the piano with one hand because he was always using the other one to fend off Mr Williams, the music master at his Yorkshire prep school. Perhaps schools were once dens of vice, but the pendulum has swung much too far when you can’t give a pupil a lift home in a snow storm, or cuddle a sobbing child who’s just been taken away from her parents.

I was depressed by the creeping erosion of freedom and fun. No more conker fights, detentions if you chuck a snowball, no playground slides, experiments in science being phased out for fear of litigation. Half the joy of physics was seeing Miss Williams emerging from a cloud of black smoke with her eyebrows singed, wailing: “But it worked with the other division.”

Consider too the poor Jack Russell cast as Bill Sikes’s dog in a Stroud school production of Oliver!, then sacked for health and safety reasons, an experience that his owners said had left him much saddened.

He might have been cheered up by the dreadful but hilarious statistic that, in a survey, 80 per cent of secondary school children thought Winston Churchill was the dog in the television advertisements for an insurance company. It makes one wonder if English history is still taught in schools.

On my travels around schools I also learned how to converse with teenagers of either sex. “What football team do you support?” or “I’ve actually met Colin Firth,” always breaks the ice. (Although, interestingly, the character that girls most frequently cite from Pride and Prejudice is Mrs Bennett: “Because she’s soooo embarrassing - like my Mum.”) To return to Katherine Eckersley. I was proud to be invited to the end-of-school prom, but I goofed. Imagining it meant some kind of promenade concert, I arrived in a crumpled pink suit only to find all the children, ravishing in ball dresses and dinner jackets, spilling out of limos. My embarrassment was soon dispelled by lashing of “teacher’s lemonade”

(bottles half full with Fanta and half vodka) as we danced to a splendid band in a hall transformed by hundreds of cut-out gold stars. When the prom king was crowned, one of his mates yelled out that it was the “first time there’d been a poof on the throne since James ...”, so they had learnt some English history after all.

When the balloons came down, the girls burst them with their stilettos to symbolise the end of a fantastic year. Outside the night was lit up by fireworks, culminating in white stars spelling out “Goodbye Village High”.

The words I heard over again as sobbing children flung their arms round Katherine were: “Oh, Miss, I’m going to miss you, Miss.”

The children’s GCSE results weren’t spectacular by beastly league table standards; only a handful had gained the magic five. But so many who had been expected to get none notched up several Bs, Cs and Ds and, fired with new confidence, went off happily to sixth-form colleges, or to learn to be hairdressers and carpenters, or take up places in sports academies.

I was unable to celebrate with them that year, but I did spend a wonderful results day at another favourite school, Barnwood Park in Gloucester. Most schools email their results, or pin them in envelopes to the noticeboard.

Gill Pyatt, Barnwood Park’s inspiring head, broke the good (and bad) news personally to every girl and was so good at praising and comforting them all.

Summoned by mobile and text, excited parents were soon storming the playground, bearing flowers in cellophane tubes and cards in coloured envelopes. One girl, flabbergasted to get the magic five, rang the factory where her dad worked and made them broadcast her results over the tannoy.

Looking back, I am touched that so many heads trusted me enough to let me wander round their schools, where I saw marvellous and imaginative teaching. “Macbeth was a killing machine on a fantastic high having routed the terrorists who were trying to overthrow King Duncan,” wrote Claire Matthews, an English and drama teacher at Archway School, Stroud. “For homework,” she had added, “if you were a costume designer, how would you kit out the weird sisters? Or imagine you’re a war correspondent, like John Simpson, and write a script telling the viewers at home about Macbeth’s first victory.”

Wandering along the corridors at Archway, I found a touching poem written by a Year 10 pupil: “Love is like rugby football, it can get a little rough.” On the staffroom wall was a sign saying: “Thought for the week: chewing gum. We’re gumming down.”

Then I remembered a postcard attached to the filing cabinet in the general office at Village high: “One man gets run over on the roads every five minutes and he’s getting very fed up with it.”

What I loved about schools is that despite the tragedies, cheerfulness always breaks in. Having my photograph taken for this piece with the girls at Barnwood Park, they told me that while eating their packed lunch in the playground, they’d been bombarded “by ginormous killer gulls”, so they’d put a pretend owl called Ernie up on the roof to terrify the gulls. As I left, however, two gulls were happily perched onErnie’s head and five others were noisily queuing up for a turn. It seemed to sum up education.

Wicked! by Jilly Cooper is published in hardback (pound;17.99) by Bantam Press on May 8. To win one of five free copies answer this question: Which of the following was not written by Jilly Cooper? a) Riders b) Rivals c) Roadies. Send your answer on a postcard or by email marked Wicked! to the address on page 3.Ever fancied giving your school the Jilly treatment? For tips on how - and how not - to do it, go to: www.tes.co.ukFridayGet+published

Every school has got one

Some of the characters fromWicked! Anyone you recognise?

Paris Alvaston Larks pupil and icon. Habitual runaway from his care home.

Rufus Anderson Brilliant and eccentric head of geography at Bagley Hall.

Henpecked father of two, liable to leave coursework on trains.

Miss Basket Menopausal misfit who teaches geography at Larkminster comprehensive (otherwise known as Larks).

Sophy Belvedon English teacher of splendid proportions and great charm.

Gordon Blenchley Unsavoury care manager of Paris Alvaston’s children’s home.

Hengist Brett-Taylor Hugely charismatic headmaster of Bagley Hall.

Sally Brett-Taylor Hengist’s wife, classic beauty and jolly good sort.

Alex Bruce Deputy head of Bagley Hall, nicknamed Mr Fussy.

Poppet Bruce His wife, who teaches RE. An “acronymphomaniac”, determined to impose total political correctness on Bagley Hall.

Maria Cambola Larks’s splendidly flamboyant head of music.

Ian Cartwright Former commanding officer of a tank regiment, now bursar at Bagley Hall.

Patience Cartwright Ian’s loyal wife.A trooper who teaches riding and runs the stables at Bagley.

Mrs Chalford Head of history at Larks. A self-important bossy boots who likes to be referred to as “Chally”.

Janna Curtis Larks’s very young, Yorkshire-born headteacher.

Emlyn Davies Former Welsh rugby international, known as Attila the Hunk, who teaches history at Bagley Hall and coaches the rugger fifteens to serial victory.

Ashton Douglas Sinister chief executive officer of S and C Services, the private company brought in by the government to supervise education in Larkshire.

Vicky Fairchild Two-faced but both of them extremely pretty. Cures truancy at Larks overnight when Janna Curtis appoints her as head of drama.

Theo Graham Head of classics at Bagley Hall. A crusty old bachelor with a heart of gold. Takes out his hearing aid on Speech Day.

Wade Hargreaves Unexpectedly humane Ofsted inspector.

Rod Hyde An awful autocrat, headmaster of St James’s (“St Jimmy’s”), a highly successful Larkminster grant-maintained school.

Mr Mates Larks science master, almost as old as Archimedes.

Mike Pitts Larks’s deputy head, furious the head’s job has been given to Janna Curtis.

Stewart Wilby Powerful and visionary headteacher of Janna Curtis’s former school in the West Riding. Janna’s former lover.