Gill Hornby on her new novel The Hive

Gill Hornby says she knew it as soon as she saw it in the gaggle of mothers outside her little daughter’s new school. “I just turned up expecting it to be like normal society, and within minutes I realised there was a sporty group, a teacher’s pet group and a rebellious group, there were social outcasts and populars – I was just back at school myself.”

Time passed. That little girl, Holly, is now 22. In the intervening years, Hornby took three more children, Charlie, Matilda and Sam, to school – “that’s millions of school days, I know what I’m talking about!” – and the story of the women at the school gates simmered on the back burner. But, when her job as a columnist for the Daily Telegraph came to an end in 2010, and her youngest son neared the end of his primary education, the time came to return to the book that had been cooking, slowly, all those years.

She had plenty of encouragement. Her husband is Robert Harris, the best-selling author of thrillers such as Enigma, Archangel, and the Blair conspiracy thriller The Ghost. And her brother is Nick Hornby, author of High Fidelity, Fever Pitch and About A Boy. “It slightly annoyed me because they both said: ‘Well, write a novel’, like everyone has to write a novel,” she chuckles.

But write it she did, between taking Sam, now 12, to school and picking him up again, and found she rather enjoyed it. “I think it came quickly because it had been cooking quietly in the simmering pan for nearly 20 years. When I did sit down, it poured out and it took on a life of its own.”

That book, The Hive, was the subject of a seven-way bidding war between publishers and led to Hornby being described as Little, Brown’s “most important new author of 2013”. She looks a little shocked by the attention. “I suppose partly I wasn’t prepared for it to sell well because statistically I didn’t think it was possible that a third member of the family could pull it off. So I just thought, ‘Well, I’ll be the lame one with a little publishing deal for £5’. The whole thing has been a bit of a surprise.”

Rights to The Hive have sold all over the world – another shock to Hornby, since she feels the story is quintessentially English (“How are they going to understand  Malteser cake?” she says, frowning) and the film rights have sold to Focus Features,  the art house division of movie giant  NBCUniversal. In her publisher’s offices for a round of interviews and photoshoots, she looks every inch the successful writer, with her stylish blonde bob and sheer powder-blue dress, but admits the whole thing is “bloomin’ terrifying”. Because, after all the hype, people are going to read the book for the first time? “Yeah. Or not, even. That would be even worse.”

The Hive is being hailed as the start of a new wave of fiction. Ever since the surprise success of Fifty Shades of Grey, publishers have been trying to second-guess the next big trend. As one newspaper put it: “After mummy porn, mumlit?” It makes sense. Women are the major buyers of fiction, but the generation who have grown out of chicklit – the grown-up Bridget Joneses who started families and moved to the country – are not well served by the market. Here is a book that is funny (there are some great comic set pieces), looks at its world with a dash of irony, while still telling real stories about real lives and families. Call it what you will – school-gate lit, mother-hen lit – it might just be publishing gold.

So, welcome to St Ambrose, a state-run primary school in a smart English market town. A new headmaster arrives with plans to turn old outhouses into a new school library, galvanising the mothers’ fund-raising committee. But as the cliques manoeuvre through the lunch ladder and the car boot sale, the school year becomes a structure in which to frame life-changing events: broken relationships, depression, cancer scares.

The small-town world of the book actually contains all of life writ-large, a technique which has been returned to of late by writers, including JK Rowling, whose much anticipated first novel for adults, The Casual Vacancy, turns on events in a small town. Hornby describes the writers she most admires – Anne Tyler, Curtis Sittenfeld, Daphne du Maurier, Elizabeth Jane Howard, the reprinted Persephone range: “They’re all like that, aren’t they? All women, all small-town, family-based, ordinary lives written well. I’m very interested in ordinary lives and families.”

She emphasises that the small town of the book isn’t her own – Kintbury, in Berkshire, which is much smaller than the town in the book. But the location was important. “In cities you get extreme wealth and glamour, and that does distort everything. I wanted it to be quite a neutral setting so I could concentrate on the female power play. I have friends whose children are at London schools and, you know, if Gwyneth Paltrow’s at the school gates then nothing is very normal, is it?”

Queen of the small world novel is Hornby’s favourite writer, Jane Austen, who famously said that “three of four families in a country village is the thing to work on”. Hornby, who wrote a biography of Austen for children in 2005, The Girl With The Magic Pen, said she thought she could do worse than give that a try. “Because life isn’t actually about status or profession, we are all reduced to our own emotional lives. That is the only thing really that matters, the rest of it is window dressing, isn’t it?

“Somebody who interviewed me said, ‘It’s so clever of you to write about the culturally invisible’. I didn’t know we were culturally invisible! We can all see one another! We might be culturally invisible to you, mate – it was a man, of course – but all I see every day, all day long, are middle-aged, middle-class women. There are millions of us. I wasn’t being clever, I was writing about what I know.”

So, let’s peel some individuals from the cluster outside St Ambrose school gate. Rachel is nursing a broken heart since her husband ran off with “the intern”, and she found – to her surprise – that her social circle don’t want to know her. Heather is desperate for the acceptance of the in-crowd, at times comically so. Georgie keeps sloping off for a cigarette, and Colette will chase anything in trousers. And of course, there’s Bea, the queen of the fundraising committee, but after a year of power struggles can she hold on to her crown?

Bea gets nastier the harder she tries to retain her throne, and the group starts to turn on her and seek a new Queen Bee. It’s all typical behaviour, Hornby says. “It’s what the tabloid press does with female role models, pop stars and actresses. They can do absolutely no wrong, then they often do start to behave badly, and then, boy, do we start despising them and bashing at them. It’s the same sort of cycle, it takes about three years. And it takes three years for an actual queen bee in a hive.”

In writing the book, Hornby has learned a lot about bees, the book’s central metaphor, another highly organised, matriarchal society. A hive will periodically feed queen cells with royal jelly, producing several potential new queens. “But the hive won’t necessarily accept them. It’s no good just being a queen bee, you have to be accepted by the workers in order to work as a queen bee. If they don’t like her, they will smother her with their wings, or drive her out and she will have to go and make something somewhere else.”

However, every time you think The Hive is just a book about women behaving badly, it undercuts your expectations with a strand of real-life. The mums of St Ambrose are going to need each other when tragedy strikes. “Something terrible always happens in a school year, something fabulous always happens in a school year, and everybody is slightly altered by the end of it. When terrible things happen, that’s the community that moves in and supports you, it’s not the people who are your soulmates who live miles away, it’s all about proximity and these are the people who know you and your children.”

The pay-off for putting up with all the power games is the formation of real friendships. “Everybody in the book makes a really, really good close friendship. We do bond. That is the positive thing about the hive, it is an affirmation of it, that we look after one another when things go very bad. And by the end of the book they’ve built a library. Without them, it wouldn’t exist.”

• The Hive, by Gill Hornby, is published by Little, Brown this week, £12.99