Why is the show so successsful?

Hank Azaria: We try to reward people for paying attention. If you don't pay attention it's a very funny show, but if you do pay attention there are lots of references to other things that are going on in our lives, in culture, in movies and so on.

Do you find your own character comes out in the parts you play?

Nancy Cartwright: We all have a little Bart inside of all of us, Bart gets away with doing the things we all wish we could get away with. Playing Nelson gives me the opportunity to be Bart's nemesis, he allows me to be this angry guy, tough and a bully. It's great fun as an actor to wrap my wits around that. Ralph Wiggum, he's a sweet innocent guy! It doesn't matter what he says, I play it and I know everyone will respond a certain way.

Harry Shearer: I play both Burns and Smithers, the main thing it draws out in me is my own deep self love! All the characters I play have a common corrupt venality - I have a well of that to draw on!

Hank Azaria: Although I play Moe, Apu, Wiggum, Professor Frink, oddly I feel like Lisa Simpson inside. I've been doing silly voices since I was a child - it's a nice outlet for that.

Are you surprised by the huge success of The Simpsons in the UK?

Mike Scully Yes, even though the script depends on American language and American usage, when we performed live in Edinburgh the laughs came in all the right places. American is everyone's second language now.

Since The Simpsons started, several darker animation shows have come along. Are there things you don't want to do with The Simpsons?

Matt Groening: We won't do what South Park and Beavis and Butthead do. We have a shared vision of where the show should go, there's a consistency of tone and an attempt to honour the characters. Coming here keeps the show alive. Animation takes incredible energy and attention, the more fun things like meeting the people who really love the show help keep it alive that much longer.

Will you do a feature film?

Matt Groening: The business answer is "no deals have been struck"! The creative answer is only if we can figure out how to do something that is not redundant, not the same as the TV show. Every TV episode is a mini-feature. But in the long run, I have no doubt we'll do a movie eventually.

Who are your favourite characters?

Matt Groening: I like the characters who have a few lines an episode. I know Homer and Lisa and Bart will get laughs but when we can get laughs out of the more obscure characters it makes me happy. My specific favourite character is Lisa because she's the only one who is going to escape Springfield!

What's your favourite line from the show?

Matt Groening: My favourite line from Homer is: "Operator, quick, get me the number for 911!"

How are the voices recorded?

Harry Shearer: We do it sequentially as dramatic episodes, so what we do in live performance is what we do in the show. The continuity and the ability to hear each other and to react to each other is why what comes out of The Simpsons is not just voice work but acting.

Are there any celebrity guests you'd like to have on the show?

Matt Groening: We have a long list of celebrities who have asked to be on the show, we just work our way down the list!