Imagine a world just like ours, but in photographic negative. Black people are the educated elite, the ruling class. White people are the minority, employed only in menial jobs, without legal rights or representation. This is the world that Malorie Blackman, one of our leading children’s writers, has imagined in detail after needing a plaster one day and being struck that they were all pink and designed to blend with a white person’s skin.

It’s something she would never have noticed but for the fact that she is black — the only black writer to have got into the top 100 of the nation’s favourite books in the BBC’s The Big Read. She did so with Noughts & Crosses, the novel that describes this inverted world and the doomed love between a black “Cross” girl, Sephy, and a white “Nought” boy, Callum. “It was such a thrill to be on that list,” she says, as we talk in a London hotel, “but I kept scanning the room for more black faces and thinking, where are all the others?”

Filled with love, sorrow, suffering and stinging satire on injustice, Noughts & Crosses is a remarkable novel, not least in tackling the subject of race with brilliant simplicity. Every page shocks; Knife Edge, the sequel, is no less impressive. The style is simple and direct, but the ramifications of what it describes are thought out in devastating detail. Children’s fiction has long been the repository of great satirical writing, but Blackman’s trilogy takes it into levels unseen since Orwell’s Nineteen Eighty-Four. It’s a hard trick to pull off: Hollywood tried with White Man’s Burden in 1995 — starring John Travolta and Harry Belafonte — but the film was a flop.

Blackman seemed like the last person to write such revolutionary fiction because what she was known for, until very recently, was being a black author who didn’t make an issue out of colour. Prize-winning novels such as Pig-Heart Boy (filmed for the BBC) and Hacker presented child heroes who happened to be black — ordinary people in extraordinary situations. In person she is a woman whose infectious laughter makes her seem like the opposite of Jude, the hate-filled terrorist murderer whose mind we inhabit for almost half of Knife Edge. She did, she says, “find it hard to write him”; nevertheless, the violent racism she describes in her inverted world springs from personal experience as well as observation.

“When I see a group of white boys, I get nervous. Last year in Bromley I was coming out of Sainsbury’s and got called ‘jungle bunny’ and spat on by a group. Black guys have called me a slag because my daughter is mixed-race. I think things have got worse, but I remain hopeful. I am an optimist — a pessimistic optimist.”

To a white reader the Noughts & Crosses world seems more reminiscent of South Africa under apartheid than modern Britain. Surely it is comforting, I say, that in Britain what matters is your education, not your race. Blackman says: “Only if everyone is on a level playing field. Education has become a privilege, not a right.”

Blackman, brought up in Hounslow, West London, went to a grammar school; her father was a carpenter and her sister is a probation officer. She is married to a Scot, and their eight-year-old daughter is at a fee-paying school. “I go to schools all over the country and in too many of them teachers say to me, ‘Oh, don’t expect much out of these (black) boys, they aren’t creative.’ I think, ‘How dare you! They’re only 8, 9, 10 and they are being expected to fail.’ What I always tell children is that education is a leveller. If you’re educated, nobody can say, ‘You can’t’. But getting that confidence . . .” She sighs. “You can do it if you believe in yourself and are prepared to work hard for it.”

She loved English at school, and wanted to train as an English teacher at Goldsmiths, but was told by her careers adviser that she would do better to get a business degree at the local polytechnic. Bored, she began to write, and for the next ten years, while she worked in computing, eventually as a manager at Reuters database, she endured rejection after rejection from publishers. While growing up she had loved reading myths and fairytales as well as Enid Blyton and the Chalet School books. But it was only when she read Alice Walker’s The Color Purple that she realised she could become a writer too. “I wanted to read books that had me in them,” she says. “I loved fantasies, mysteries, love stories. It was the dearth of black children in those that made me determined to do something.” What she could achieve was underlined when, as a girl, she read a series about black pioneers — realising that the first person to reach the North Pole (Matthew Henson), the pioneer of blood banks (Dr Charles Drew) and the first doctor to perform open-heart surgery (Dr Daniel Williams) were all black.

“I go to a black women’s writers group and found we’d all been told at school, ‘Black women don’t go to college’. It’s such insidious stuff. Kids are still amazed when I walk in and they see that you can be black and a writer.”

Even when she found a publisher, it was made clear to her that she was expected to “write about race and nothing else. But I like to confound expectations.” She grins, wickedly. “A couple of editors did say, ‘We want something for our multicultural list, and I’d think, ‘Well, you’re not getting one from me.’ I wanted a black person on the cover, but plots that had nothing to do with race per se.”

In fact, her black friends were against her writing about racial issues such as slavery. But after 11 children’s novels (and 49 children’s books in total), she felt she had earned the right to write Noughts & Crosses. When she addressed racism, it was to turn it on its head.

“What I always want to do is to show what it’s like to be in someone else’s shoes,” she says.

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