“She doesn’t treat anyone like an equal. That’s the way she’s been brought up. She’s like her father; but she still manages to have moments of kindness.”

Chibundu Onuzo is defending the protagonist in her debut novel, The Spider King’s Daughter. She sits opposite me in an airy delicatessen in London Bridge, a fork dancing in her hand, her youthful face animated. She’s supposed to be eating a plate of mushroom pasta, but after I suggest her story of friendship across Nigeria’s economic lines cannot really be a friendship when the rich man’s daughter, Abike, insists on referring to the book’s other central character as The Hawker, denying him an identity beyond his poverty, Chibundu launches an earnest defence.

“She was raised in a very unhappy home. I applaud Abike for all her humanity,” she insists.

Chibundu is softly spoken and self-effacing. There can’t be many 21-year-old university students who find themselves juggling essay deadlines with promotion for a published novel, and there are certainly no others who can claim to be the youngest female writer ever signed by the venerated publishing house, Faber and Faber.

“Theoretically there’s more than enough time,” Chibundu, whose name means God is life, says with a wry smile, “There are 24 hours in a day. If I was a good, organised person, I could do everything and even take up hockey or something.”

It is a typical response from the young author, a mild self-depreciation used to counter any suggestion that her achievements are extraordinary. I’m not convinced. After all it must take a certain amount of focus and a prodigious amount of talent to secure an agent on the strength of three chapters then land yourself a two-book deal at 19. The subsequent two years of manuscript revisions were done alongside a history degree at King’s College, and now, in her final year she’s simultaneously working on her sophomore novel.

When does she find time to write, I wonder. “My days are upside down,” she admits, “I can write until 5am. Obviously that doesn’t work when I have lectures but you don’t get the same quality of silence during the day. At 2am it’s like you’re the only person in the world.”

Despite her amiable demeanour I imagine it must have taken some tenacious persuasion for her parents to agree to her history degree, a subject usually considered about as useful as horse husbandry by Nigerian parents.

She laughs, a hearty sound that peppers our conversation, and nods in agreement. “Luckily for me I’m the youngest, they were just like,” she switches from her lightly accented English to a heavier Nigerian vernacular, “…go to university, get a degree and hurry up. We don’t care what you do, you can do nail cutting studies. Just go to school and come out and let us go into our retirement.”

With her older siblings already working in law, finance and engineering, her parents, both doctors, probably decided three out of four was good enough.

They likely also noted their youngest child’s ambitious streak – “I started my first novel when I was 10. I wrote 70 pages. When I was 14 I tried a short story collection.” – and realised it wouldn’t matter what she studied. After all, successful author is just another objective on a long list. Ultimately she’d like to work in politics or social development: “I haven’t decided if it would be more effective to work outside government…” not to mention the singing interest she’d also like to explore along the way.

Chibundu first came to Britain to attend a private boarding school at 14, a familiar trajectory for the children of Nigeria’s upper classes. I ask about the issue of class and wealth in Nigeria, a theme that underpins her novel.

Her seventeen-year-old creation Abike lives in a sprawling mansion, the favourite child of wealthy businessman, Mr Johnson, a man with his hands in every pie, (hence the title). On the opposite end of the spectrum is the young street hawker who one day sells Abike an ice cream, and changes the path of both their lives. Would these two really meet? Could they have a relationship in Lagos, a city where the gap between rich and poor is a yawning chasm?

“Yes!” Chibundu is adamant, her hands emphasising points as she talks. “In Nigeria we talk to each other more. Strangers strike up conversations.” She refers to an incident described by author Colin Grant at the Black Book Swap, an anecdote about a colleague at the BBC who doesn’t see or acknowledge the staff that clean their offices. “In Nigeria that wouldn’t happen, the cleaner would say, ‘Good morning Oga,’ he’d ask, ‘How is the family?’ there’d be that interaction.” She goes further arguing Nigeria doesn’t have a class system at all. “We call them levels. The levels are fluid, you can always move up or down.”

The delicatessen has grown steadily busier around us and I pull out my final questions. I admire her hair and wonder at the reaction in Nigeria, a country that only seems to appreciate the afro on black Americans. She laughs again, “people think it’s a wig,” she says bemused, “they forget this is the way God made our hair.”

What about identity? “I never thought of myself as black until I came to the UK. In Nigeria we use tribe to differentiate – to create artificial differentiations I think. I don’t mind being a black author; I’m black, I’m Nigerian. It’s in the nature of people to look for ways to classify.”

Her favourite childhood books? Interestingly she grew up with the same pool of imported Western classics as Nigerian children growing up in the 60s and 70s -The Famous Five, Mallory Towers and later Jane Eyre, Wuthering Heights, David Copperfield and The Count of Monte Cristo.

Her eyes light up when she mentions Chinua Achebe’s Things Fall Apart, though she was only inspired to read it once she’d moved to Britain. “I just had this thought in my mind that Nigerian fiction would be very dull. I read it in one sitting. And I thought, ‘this book is amazing, I’ve been missing out.’” From there she discovered Chimamanda Ngozi Adichie and Sefi Atta.

“I met Chimamanda  – she was very nice,” she says in that endearing, off-hand way that I imagine must become habitual when extraordinary things form the regular wallpaper of your life, “I mentioned the book, she said yeah, she’d heard about it.”

Chibundu joins a growing community of African writers being lauded on the international stage. Writers who, like Achebe did a generation ago, are telling African stories on their own terms. “When Ben Okri won the Booker prize in 1991…” she muses, getting the Booker year so dead-on I know she must have considered the prestigious award with her own name on it, “he must have felt a little lonely because he was one of very few African contemporary authors writing internationally. Now there are so many.” Indeed, so she can rest assured she won’t feel at all lonely when she gets hers.