LONDON, England (CNN) -- The most eagerly anticipated animated film this year hits big screens this weekend, as "The Simpsons Movie" opens worldwide. The Screening Room spoke to creator Matt Groening and writer Al Jean in London about everyone's favorite two-dimensional yellow family.



Simpsons supremo Matt Groening with his creations at the film's premiere in Springfield, Vermont



Matt Groening told the Screening Room that fans had driven the demand for the movie. "We've had fans clamoring for a movie for the past 18 years," he said.



The film has taken four years to come to fruition, as writer Al Jean explained. "What really held us up for a long time was to have enough people to do the show and the movie," he said. "We talked for a while about doing the movie after the show is done, but the show is never done! So it really started in earnest in 2003, when we started working on this story that became the movie."



Technology has also played its part. Jean continued, "The technology to do this film really wasn't even around five years ago. For example, there was this joke I once pitched and David Silverman, the director, started drawing and as I was pitching it, it went into the film and it was cut a day later. To go from pitch to cut in two days is pretty impressive."



Its creators hope that "The Simpsons Movie" will both satisfy long-term fans and bring Homer and Marge's family to a new audience. Groening told the Screening Room, "This movie is designed to both honor the people who have loved the show all this time, so there's lots of little details for them in the movie, little characters and stuff who they know and love, but we also want people who don't know the family to not be completely confused. It is a complete movie experience, but again, we have a lot of little details that only the really, true die-hard fans are going to get."



And fans can expect to be entertained by plenty of cartoon mishaps. Groening said, "When you see somebody fall off the roof in a live-action film, it's funny -- we all love it. But it's not as funny as when Homer falls off the roof. I don't know what that says about humanity, but we do like to see cartoon characters hurt themselves and there's quite a bit of that."



But how have Springfield's finest led the field for so long? Groening believes that a large part of the Simpsons' success is down to the traditional animated techniques used to create it -- and that its hand-drawn charm puts the movie ahead of its CGI rivals. He told CNN, "The difference between our film and these other films is that we have no penguins, okay? So that's the big difference. (Although we do have one penguin.)



"But the other thing is, our film is done the old fashioned way. It's got a lot of errors and flaws in it. These computer-animated films -- and I love them -- are perfect. They're spooky, they're so good. Ours is a way for us to honor the art of traditional animation."



Al Jean thinks that the series' success is also down to its wide appeal. He says, "I have a two year old and she loves the Simpsons already, just because of the way it looks and the family. And then on the other hand, we do satirical references that only an adult would get."



A large part of the appeal of "The Simpsons" comes from its ability to portray the more touching moments in family life, like Jean's favorite moment in the movie. "It's a scene where Bart is really mad at his father," he told CNN. "He's sitting in a tree outside the Simpson house at night. He looks over and sees the Flanders house and thinks how wonderful it would be if he lived there
What techniques are used? What did Simpsons creator Matt Groening say? What does Matt Groening say? What did writer Al Jean say?
traditional animated "We've had fans clamoring for a movie for the past 18 years," "We've had fans clamoring for a movie for the past 18 years," explained. "What really held us up for a long time was to have enough people to do the show and the movie," he said.
question: What techniques are used?, answer: traditional animated | question: What did Simpsons creator Matt Groening say?, answer: "We've had fans clamoring for a movie for the past 18 years," | question: What does Matt Groening say?, answer: "We've had fans clamoring for a movie for the past 18 years," | question: What did writer Al Jean say?, answer: explained. "What really held us up for a long time was to have enough people to do the show and the movie," he said.