At Cambridge, it was the weirdest culture. Everyone pretended they didn't do any work, yet it was so competitive.

One of the saddest aspects for me about filming in South Africa was that the real inequalities are still very much in place - and those are economic inequalities.

I definitely felt frightened [on Skyfall], but never in danger, because they were always so careful about everything. Some of the driving, particularly on that road around the sheer-drop cliff was actually done by stunt driver Ben Collin, who is otherwise known as The Stig from the TV show Pop Gear. He's a brilliant drive, nonetheless, it was terrifying to be careening along when a wrong turn would mean a thousand-foot drop and you're not in control and you want to slow the car down.

I always find filming stressful. I get very caught up thinking about my character - 'Am I doing it right? Should it be done this way?'

I wanted to play roles which offered new ways of viewing black women and black people in general- and I have done that. And I have always, whether I needed to pay the rent or not, I've always turned down roles which I thought were stereotypical. And so when I look at my body of work in that respect, I am really happy. Because I feel my work does say something positive and that was what I always set out to do.

Only do acting, if you don't want to do anything else. And know that it's a tough journey with a lot of rejection along the way. You have to have a lot of self-belief.

I think there's nothing more amazing than helping people every day.