Mat Whitecross, 31, started making films at 13 using his father's camera, a toy gun and lots of ketchup. 'Someone would enter a room and kill about ten people and that was that.' While studying English at University College London, he met an unknown band called Coldplay and directed their first video, Bigger Stronger.

'We shot it on the beach in winter and I made Chris Martin jump off a cliff into the ocean. It was haphazard and shambolic, but great fun.'

After working as a runner and editor, Mat co-directed the documentary Road to Guantanamo, about prisoners released from Guantanamo Bay, with Michael Winterbottom in 2006. 'I had the idea but nobody would give me the money to do it, so Michael suggested we do it together. We were both quite drunk, but the next day he got the ball rolling.'

Mat is currently finishing another documentary, Moving to Mars, about Burmese refugees in Sheffield, a subject that is close to him because his parents were political exiles from Argentina. 'My mother was an Argentinian teacher, my father was English and worked in publishing. When Argentina became a dictatorship in 1976, they harboured Chilean refugees. They were in prison for six months. My English grandfather launched a campaign with Amnesty International and they were freed, but exiled.'

What inspired you to direct?
We used to live next to a cinema in Oxford, so I grew up watching films. At school they told me to become a librarian because I was into books. Thankfully, I didn't listen.

What are Coldplay like?
Their record company wanted them to wear shades and walk in slow motion, and they just wanted to be filmed looking like idiots. So that's what we did. I have memories of pushing Chris Martin around London in a supermarket trolley.

What's better, drama or documentary?
With a documentary, you enter somebody's life. You're supposed to observe objectively, but you can't help forming a bond. Drama carries great freedom, because if something screws up you can do it again, but is a nightmare because you have limited time and money.

Who do you admire?
Michael Winterbottom because he's constantly pushing himself and coming up with new ideas.

What's next?
I'm working on a script for a film on Alzheimer's, because my dad had the disease.

Mat's first feature film, the Ian Dury biopic Sex & Drugs & Rock & Roll, is out next year. Moving to Mars will premiere on More4 in November