There is, in short order, going to be a family movie blood bath at the box office this holiday weekend, with “Arthur Christmas,” “Hugo” and “The Muppets” all arriving in theaters. While all three films certainly deserve merit, “Arthur Christmas,” with its surprisingly complex themes and glittery animation, is probably the most unexpected and the least pre-sold (since it’s not based on a best-selling book or long-running franchise). But don’t let its underdog status fool you: this is big, bright, bristling piece of entertainment and totally deserves your Thanksgiving dollars. We got a chance to speak to “Arthur Christmas” co-writer/director Sarah Smith and co-star Bill Nighy (who plays Grandsanta) about what it was like to be part of a new holiday classic.

Sarah Smith has a background in British television, having worked on “The League of Gentlemen” and “The Armando Iannucci Shows,” and was brought to Aardman to help get their upcoming slate in order (including next spring’s “The Pirates! Band of Misfits“), but as development on “Arthur Christmas” wore on, she found herself getting more and more attached. “It became my baby,” Smith told us. “And I just couldn’t bear to let it go.” When she proposed that she be the director, at first they weren’t quite sure. “I said, ‘I really want to make this movie!’ And they looked a little startled, as I’d never done animation before. But they were brave enough to back me.”

Not only had Smith never done animation before, but she had never directed a feature before. The process was overwhelming. “It was the most incredibly exhaustive experience,” she says flatly. “People have no idea the complexity that goes into animated movies. In live action the most intense part is the shoot, which can go on for four or five years in animation.”

Still, once she was in the thick of it, she made very strong decisions, and while she says that she “wanted it to bear a relation to other Aardman movies,” like the ‘Wallace & Gromit‘ films, a different ethos governed the production. “The whole look was defined by ‘it could be true,'” Smith told us. “I wanted the world we created to very much be a child’s real world so that it was contemporary, but that the whole world would feel transformed in the way that it does on Christmas night.”

There has been much written about the place of female filmmakers in animation, particularly after Pixar arbitrarily dismissed Brenda Chapman from next summer’s “Brave” (and booted her from the vaulted Brain Trust), and that outsider status could be applied to Smith for a number of reasons. “It’s tricky for me, since not only am I female, which they’re not used to, but even more significant is that I don’t come from an animation background,” Smith said. It was important for her to make sure people that had been doing it for decades didn’t feel displaced or undervalued.

And there are some of her favorite holiday movies in “Arthur Christmas,” too. “The two I love that made their way into the movie are ‘Planes, Trains and Automobiles,’ which is kind of a crazy road movie between two mismatched characters, which is very much our movie,” Smith said. “And the other is ‘The Snowman,’ a beautiful 2D thing about flying, and I wanted to capture a little bit of that.”

On casting the film, she had an eye towards the Santa family standing in for another famous British brood. “We wanted them to feel like the British royal family so I wanted to go to the British royal family of actors,” Smith said with a laugh.

One of those actors was Bill Nighy, who plays Grandsanta, the grumpy old member of the Santa family who longs for a return to the spotlight. Nighy said that despite his status in big time productions like “Love Actually” and “Pirates of the Caribbean: Dead Man’s Chest,” he still had to audition for the role. “They were looking for a four-foot tall guy with no teeth and no hair and he’s 136 years old and they thought of me,” he explained. “There’s two ways to take this: one is to be very flattered, like, ‘Oh they admire my range.’ The other is to get very worried.”

Unlike his director, though, he didn’t try to make his character relate to any real life royals. “I’m not a royal family watcher,” Nighy said. “I’m try not to think about it. I’m not an enthusiast for the British or any other monarchy. I don’t mind when it’s in another country but when it’s in mine it’s embarrassing.”

Earlier in the year, Nighy starred in Gore Verbinski‘s terrific animated western “Rango,” a process that was altogether different than “Arthur Christmas.” “Gore Verbinski assembled everyone in the room and you did it like you’d be doing a play and they filmed it,” Nighy explained. “With ‘Arthur Christmas,’ it was the more familiar process of it’s just you, on your own, in a booth.” When he finally saw “Rango” at home he said “it completely blew my mind” but was quick to note that he loves “Arthur Christmas” just as much: “I think they’re both really cool.”

While they didn’t use any of his facial expressions or bodily movements for the character, since Grandsanta was designed well before Nighy was hired, it didn’t stop him from twisting himself up to play the role. “If you had footage of me recording I probably screw myself up physically in order to try and be the 136-year-old,” Nighy said.

When Nighy initially read the script he was struck by its potential. “I thought if they do it halfway decently it will linger; it will be a perennial Christmas movie.” This was a sentiment he shares with his director, Sarah Smith. “One of the the really tough things for anybody in animation is you spend years and years of your life, and then it’s gone!” Smith laments. “It would be lovely if you could make a movie that could find a perennial place in people’s affections.”

They don’t have to worry: “Arthur Christmas,” which opens today, will be around for a long, long time.