At school black kids called me a coconut

David Oyelowo was never destined to be an actor. His Nigerian father, for whom education was the fundamental key to betterment, wanted him to become a lawyer or a doctor. As a teenager, Oyelowo traipsed along to a youth group run by the National Theatre in pursuit of a girl he fancied. Then, it was only because of a Tube strike, which held up two other kids on the way to casting, that he landed the lead in an NT youth show. "I was asked to read the lines, just to fill in, and wound up with the part," he says, grinning.

Today, at 30, Oyelowo is one of a handful of successful, high-profile, black British actors, best known as the impulsive, glamorous Danny Hunter, in Spooks, who was killed off last year at his - Oyelowo's - own request ("I wanted to go out with a bang, literally, so that, when the mortgage starts pinching, I wouldn't be tempted to phone them up and say, oh please, can I come back?"). His appeal as an actor, however, lies not only in the placid beauty of his face, but in his true versatility. The first black man to play a King for the Royal Shakespeare Company - his Henry VI preceded Adrian Lester's Henry V at the National Theatre by two years - this month, he plays a terrified father in the BBC drama Five Days, about the apparent abduction of a woman and her two children, and can also be seen in The Last King of Scotland.

And Oyelowo's versatility, in turn, surely stems from his extraordinary childhood - from the grimy Holloway Road in London to a region of Nigeria in which, it turns out, his family have royal blood. The name Oyelowo means '"A King Deserves Respect', he says. "My dad would tell me this when I was a child, but I didn't believe him. I was born in this country, and the only royal family I knew was the British one. Then we went back to Nigeria and lived on Oyelowo Street, and I found it was all true."

His dad, a prince, came to Britain in the Sixties. "He wanted a good education, so he headed straight for Oxford." On a trip home to Africa he fell in love with Oyelowo's mum and back in England, they lived at first on a council estate in Tooting Bec. "It's true there are a lot of royal families in Nigeria," he concedes. "They're kind of a dime a dozen really. So it's not like being the King of England, but more" - he pauses and laughs - "like being the King of Islington."

Oyelowo is dressed for the street when I meet him, in baggy jeans with a long chain hanging from one pocket, a T-shirt and cloth cap, yet speaking with the accent of the classically trained Shakespearean actor. At the age of six, Oyelowo went back to live in Nigeria, where his dad worked as a manager for the national airline and his mum for a railway company.

Was it a comfortable existence, being royal? "Not really. I mean my extended family are well off, but my dad didn't want to sponge off them. All my parents' money was pumped into private schooling for me and my two brothers. So we had a middle class kind of life, but a very working class kind of existence.

"In the day we'd be sent to school alongside the sons of presidents, and then we went home to a tiny two bedroom apartment. Education was everything to my father." It wasn't idyllic, by any means, he says. The kids ran around barefoot and the weather was fine, but the best thing he took from Nigeria was the "the power of being in the majority as opposed to the minority". "When I came back to England, I didn't have a minority mentality. There was nothing this society had to offer that I didn't think was mine, because I hadn't had that idea drummed into me during those formative years."

Yet, on their return to London, to Islington as it happened, Oyelowo found himself in a tough north London comprehensive where black boys had given up even trying. When he was 13, his parents could no longer tolerate the endemic corruption of everyday life in Nigeria. "We were in the red hot eye of a military government and its corruption pervaded everything. We were allowed to live in Britain, so we came back."

At his boys-only state school in Highbury, he says, he was given a tough lesson in what it meant to be black, male and British. And: "It saddened me, more than anything. To see that somehow, somewhere down the line, young kids had decided that being black was synonymous with underachieving and playing truant and having underage sex - and lots of it, with lots of different people.

"The fact that I was someone with aspirations, who wanted to do well at school, apparently warranted the nickname coconut, meaning I was black on the outside but white inside, when in fact the striving for self-betterment is very much an African thing." He was regularly bullied at school, even beaten up.