The Tricycle tackles multicultural London

These stories are about black Britain, of course, but also about Britain as a whole. As the season title suggests, it's not black and white any more; there's a huge grey area of things in society that concern us all and don't split along simple black/white lines.

I had in mind to write a play set in a prison both because my cousin, a prison officer, had given me some great stories about life on the inside and because when researching an earlier play, Slow Time [set in a young offenders' institution] in 2005, I'd spoken to a lot of inmates and officers, and what they said stayed with me.

Category B is about power and the abuse of power —and everybody in the play thinks the power resides with them. The screws and prisoners are working together so they can all have an easier life; Saul [a prisoner] runs the wing with no trouble and the prison officers love him for it, but then Saul's number-two position becomes vacant and it becomes obvious that with one too many compromises the whole system can fall apart. What I wanted to show was how flawed the prison system is.

It is not a play about race. It is a fact that a disproportionate number of those behind bars in this country are black but I didn't want to approach this from an outraged point of view. It is happening and we know it's happening, so there is no drama in that.

Most of the time the best theatre comes from outside our experience. Actually, I think theatre is leading the way in describing multicultural life in Britain, even though most artistic directors are white and middle-class. It's television and film that need to catch up.

I certainly wouldn't want to enter politics; working in the arts allows you to pose questions in more interesting ways

My perception is that black writers are not encouraged to write about big ideas. Rather, we are encouraged to write about things that concern white people — about young black men and gun culture, for instance — but don't feel comfortable saying it themselves, so they will commission a black writer to do so. We're not encouraged to write about politics.

I'm happy to describe myself as a black playwright but I believe I write about universal issues, and the fact that my plays are performed abroad — in America, South Africa, Pakistan — is evidence of that. They have themes of diaspora, immigration and integration, which affect so many different people and countries. Much of my earlier work was based on my mother's experiences as part of the Caribbean diaspora and Nicolas Kent's concept for the season excited me because it's a look at the multicultural London she helped to establish.

The starting point of Seize the Day was reading that more than 40 per cent of Londoners claim to be part of an ethnic minority. I thought it would be fun to explore the idea of a black man, Jeremy Charles, running to be Mayor of London. I have been asked if Jeremy is based on me — but he isn't. I wouldn't want to enter politics; working in the arts allows you to pose questions in more interesting ways.

When Boris Johnson was elected I realised that someone with the right level of celebrity can walk into the second most powerful office in the country. And after Barack Obama's election, people started to ask whether we would ever have a black Prime Minister. I couldn't help wondering, could a Jeremy be elected Mayor and go on to penetrate the upper echelons?

Jeremy is part of the black middle class, which is minute in Britain at the moment, and much of the play is about his relationship with a streetwise young guy, Lavelle, whom he mentors. I have come across a dislike of the black middle class among young black men such as Lavelle. They feel that my generation has accepted the status quo, and in that sense Seize the Day is where race and class meet.

I feel privileged as I have been encouraged to write about what I want to. There have been no limitations on my career

I was amused to see someone objecting to Not Black and White, saying that if it was an all-white season people would cry racism. But almost every other theatre season is all-white.

I'm not bothered whether I'm called a black playwright or just a playwright — it's all the same to me. I know some people might say I tick all the boxes — young, black, female — and that I've been pushed forward because of that, but that's their problem. I just think I've been very lucky that people liked my first play and it went from there.

Some of my black friends feel they are defined or limited by their colour but I don't. I have been privileged as a writer in that I have been encouraged to write what I want to write about; I can honestly say there have been no limitations put on my career. I feel totally comfortable with who I am and I think a big part of that is having grown up in a multicultural city such as London.

I'm still a new writer [Detaining Justice is Agbaje's third play], so the reason I write black characters is because it's what I know. I wanted to be an actress when I was younger and I knew there were never going to be enough roles for me as a black actress — my agent was never going to put me up for the blonde roles, was he? — so I deliberately put parts for people of different ethnicities in my plays.

Detaining Justice is about an illegal immigrant from Zimbabwe whose sister tries to help him by engaging a top lawyer, someone in turn who is fighting his own demons. I wanted to explore what happens when a person finds themself in a hopeless situation like this. Where do you go to for help? Do you try to do something yourself, or do you place your trust in God?

I don't know if there are right or wrong answers when it comes to immigration because we're all looking at it differently; there will never be a one-size-fits-all solution. All I can say is that I knew I wanted to write on this subject because I feel very strongly about immigration — my parents came from Nigeria and I might not have been born if they hadn't come here. You could say it's a play about race or a morality play but I really would say it's just a slice of life.