I first met them when I was volunteering in South Africa. At the time, I didn't have any plans to make a film. One of the projects we were working with was the Agape orphanage. So I met the kids and spent three months working with them, and then came back to continue film school and decided that it would be really cool to go out and make a film with them. So we returned in 2004. And it was really useful, the fact that I had volunteered there before, because when we turned up, the kids already knew me and really trusted me and were comfortable with us.

The kids have just got a real strength of spirit. And they are so positive. And I think that's why audiences actually feel quite positive after watching the film. Even though some of the things it deals with - such as AIDS and HIV in Africa - are really terrible things to comprehend, the film actually inspires people, and they come out quite positive, because the kids' personalities and spirit are so strong.

Well, they sing all the time. It's the one thing that everyone can do together. Not everyone can speak at the same time, but everyone can sing at the same time. So it's this thing that's so important in families and in communities in South Africa, as a way of getting together to celebrate joy, but also to get through sad times together and to help each other and give each other strength. So the music took on a really important and poignant part of our experience. And in the film, it became very, very important. So when we saw Slindile singing at the funeral of her brother, it was just so deeply moving and powerful, because we knew how much it meant to her, that she was singing songs that her mother taught her when Slindile was very young. She was 9 when she lost her mother, so it got into a level I had never experienced before.

We were very, very fortunate that the family was willing to share those moments with us and that they were open to us being there. But those moments were often difficult to navigate in terms of what was appropriate to film, and what was not. Usually we would sit down and explain to them that we would like to film, but that the decision was totally up to them.

But from very early on the whole family really understood the value in sharing their story with other people so that other people could understand what it's like for one family to go through this experience - because it's happening on such a wide scale. And you hear a lot about all the millions of people in Africa that are affected by this issue, but you never really see how it affects one family. So we are really, really fortunate that the Moya Family understood that right from the beginning, so that whenever there were these personal moments, they were comfortable sharing them with us.

Well, we really want audiences to take action, and there are various things that people can do. They can buy the soundtrack CD. And 100% of the profits from that go directly to help the kids in the film. Another thing that people can do is go to KeepAChildAlive.org, which is Alicia Keyes' charity, who are doing incredible things to help people in Africa get access to the drugs that are helping people live with HIV instead of it being a death sentence. They can also go to our web site - WeAreTogether.org - to find out various ways that they can help people affected, because it's a really important issue.

They're doing really well. They're older. Every time I see them, it's shocking how much older they're getting. Slindile is in her final year at school, and she still wants to be a nurse, so she's studying very hard, and doing very well. Through the film, we are helping pay for education costs for the kids to go to school, so we are helping support her through that. All the kids recently came to England, and they performed at Nelson Mandela's concert, his 90th birthday at Hyde Park. It was an amazing event. Huge, huge concert. And they sang with Annie Lennox, so that was great. It was great to see them.