Last week Malorie Blackman became the first black British writer to have sold 1m books — something that may come as news to those who see Zadie Smith or Andrea Levy as the champions in their field.

A leading children’s author, she has grown in stature as well as sales as a result of her extraordinary Noughts & Crosses trilogy, about a world that is a photographic negative of our own.

It grew out of simply noticing that all sticking plasters were pale pink. What, thought Blackman, if they were all dark brown? From this grew her version of Romeo and Juliet, in which white people form the underclass, and blacks have the good jobs and power.

A privileged black girl, Sephy, falls in love with the poor white son of her family housekeeper, has a baby by him and becomes involved in revolutionary politics.

A dark and passionate tale told by a variety of narrators, it seems completely different from the warm and humorous personality of Blackman herself. Many believe she would make a brilliant children’s laureate — the current laureate, Jacqueline Wilson, was appointed a few weeks ago. She would be the first laureate from an ethnic minority and the first black one. It’s something she says she’d find interesting to do one day, not least because of the shock she still causes in schools up and down the country when they see her.

“I am a black British writer, but when I sit at my computer to write, I’m just a writer writing for children,” she says. “I live in fear of being pigeonholed. I didn’t want to address questions of race in the beginning. I waited until I’d earned that right.”

She began by writing stories about protagonists who “just happened to be black”, having gradually noticed in the libraries she haunted as a child how people like herself never appeared in books.

Blackman herself only discovered American black authors such as Alice Walker and Toni Morrison as a young woman, at about the same time that she found out about all the black explorers, inventors and doctors who are mentioned at the end of Noughts & Crosses, who never appeared in her history lessons.

As a depressed office worker and an aspiring writer, she queued for hours to meet Walker and her heroine wrote “Don’t give up” on her copy of The Color Purple, after hearing that she had had 82 rejection letters from publishers. And she didn’t.

Having shone at English under a wonderful teacher at her girls’ grammar school in Peckham, southeast London she wanted to be an English teacher but was discouraged from even applying for university, doing computer studies instead. “When I was a child I thought everybody was my friend, and when I was a teenager I thought everyone was my enemy,” she says.

The daughter of Barbados immigrants who divorced in her teens, she grew up in south London in the 1970s and 1980s, at the time of the Brixton riots, when Enoch Powell was telling black people to go back to where they came from, and an entire generation felt criminalised because of the “sus” laws that allowed them to be arrested on mere suspicion of wrongdoing.

All of this has fed into the world of Noughts & Crosses, which has struck some white critics as extreme, but which is all too resonant with the youngsters who are Blackman’s fan base. She points up racial bias by including photographs of white victims and news stories in Knife Edge, the second book in the trilogy.

Terrorism, she observes, doesn’t happen in a vacuum, and although she makes it crystal clear how she deplores violence, she also makes adult readers uncomfortable with her descriptions of the conditions under which it seems inevitable.

She could have remained as angry as Jude, the murderous brother of Sephy’s lover, and ponders the question of why black boys do less well in school.

“It’s not a question of innate ability — in primary schools, black boys do as well as black girls and white boys. It’s in secondary schools that they are excluded in disproportionate numbers. At my own school when a black boy and a white boy were fighting, the teacher would always blame the black boy. I believe it’s not deliberate cruelty, but ignorance.”

In the absence of a grammar school in her area, she educates her nine-year-old daughter privately. “Everyone who can scrimp and save does this because my generation went through a lot of negative things, and more of my black friends than my white friends send their children to private schools,” she says. “We are either paying for a good education, or home schooling. We want the expectation that everybody will do really well. We don’t have any faith in state education, it’s a bit too ‘exclusive’ in the wrong sense of the word.”

Her own experience of coming first in tests but being told “you don’t deserve that”, and being given a C, she gave to Sephy’s “Nought” white lover, Callum.

Paradoxically, it might seem, Blackman is married to a white man, Neil, whom she clearly adores. Elegant and stylish, she exudes laughter, not anger, when describing the weird things she has discovered about how white people see black people; she wears a large silver cross round her neck, and prays daily to God while loathing the divisiveness of religion. We talk about the recent trial in the US of the Ku Klux Klansman.

“These cases need to have the light of day shone on them,” she says quietly. “The fact the accused was in his eighties is beside the point. He got away with the murder of three people. Although these things happened in the past, there is more justice now. Justice must be seen to be done.”

Beneath their dramatic plots, Blackman’s novels show how children and adults struggle towards forgiveness, compassion and understanding. It is a journey she made herself and which is repeated in the conclusion to her trilogy, Checkmate, as Sephy’s daughter Callie comes to terms with her mixed racial inheritance.

“As a teenager I saw everything in terms of black and white,” she says. “But as I grew up and asked more questions, I realised life isn’t that simple. I was an angry teenager but I had to make the choice about whether I was going to live my whole life angry, or whether I was going to let my anger go and get on with living. I was very aware of making that decision, that I was not put on this earth to have anger as my epitaph,” she says.

Checkmate by Malorie Blackman is published by Doubleday, £12.99