In a warehouse on a corner of an industrial estate on the outskirts of Bristol, the next instalment of the adventures of an absent-minded inventor and his rather more intelligent dog is slowly - very slowly - taking shape. Friendly teams of animators work with quiet intensity in the gloom of the basement. Upstairs, it is as though the artists Jake and Dinos Chapman have turned their attention to some of Britain's best-loved animated characters, with decapitated versions of Gromit and plasticine limbs scattered liberally around, and sketches and prototypes for new projects lining the walls.

For Wallace and Gromit's creator, Preston Lad  Nick Park, production on their latest adventure is reaching its busiest point. The 30-minute A Matter of Loaf and Death - in which both Wallace and Gromit find romance - will form the centrepiece of BBC1's Christmas schedule, as well as marking a return to television for Aardman Animations after a successful excursion into feature films.

But while Chicken Run and The Curse of the Were-Rabbit were both big box office successes, grossing (£88m)  in the cinema alone, the marriage between Aardman and Steven Spielberg's DreamWorks was a rocky one - and was followed by a painful split.

"After doing two features back to back, Chicken Run and Were-Rabbit, they were such enormous processes to go through taking years and years, I just wanted to get back to doing something I could be more in control of again," Park says. "Because it's primarily for the BBC, I'm not getting constant notes about how it's going to work in middle America, or how some kid doesn't understand what some northern phrase is."

Towards the end, the relationship with DreamWorks became "a sort of a battle", he admits. Chicken Run, Aardman's first feature film, was "exciting" and a huge learning curve. But, faced with Park's determination to preserve the integrity of the characters he created while still a struggling film student - he came to Aardman in 1985 after its founders Peter Lord and David Sproxton spotted his talent - Hollywood executives wielding focus group studies and test screening results were always going to come off second best.

"They really wanted us to do a Wallace and Gromit film but at the same time they also had half a mind on how they could make it work in the States. That was always the question," Park says. "It was a great experience and I feel very proud of the end result. But we had to dig our heels in an awful lot. I don't mind that, it was just the effort that goes into that is a stress in itself."

Aardman fought hard to retain the rights to the characters, which left DreamWorks feeling uncomfortable about losing control of an area almost as important to the bottom line as the box office take. "They found it difficult working with characters they didn't own," says Park. "They were trying to respect that at the same time as trying to completely dictate to us. There was a sense of tension."

After the Hollywood dream turned sour, reaching its nadir with the disappointing non-Park CGI film Flushed Away, both sides walked away and Aardman signed a new contract with Sony Pictures. Park concurs that, after the animation boom of the mid-1990s with clever family films that could appeal equally to kids and adults - Toy Story, Shrek, Finding Nemo and so on - there was a feeling that Hollywood had fallen out of love with animation. But he thinks Aardman's new relationship with Sony will blossom.

The studio has three non-Park films about to be green-lit - Pirates (directed by Lord), The Cat Burglars (overseen by the co-director of The Curse of the Were-Rabbit, Steve Box) and Arthur Christmas. And, while DreamWorks was pushing the studio more towards CGI, Sony is happy for it to combine computer techniques with Park's beloved claymation.

He still recalls the moment when he alighted upon it as his medium of choice. "I suddenly saw what a magical effect it had. Everybody knows what a lump of clay is and seeing it come to life is quite a magical thing. You can see the material and see it moving and suddenly gaining a character somehow," he says.

Park says it is unlikely there will ever be another Wallace and Gromit movie, but more television specials remain a possibility. He adds he also has an idea for another feature but is concentrating on A Matter of Loaf and Death for the time being. "All of our stuff has taken time to grow on people. It started small and had this long, slow, organic growth. You can't knock stuff out quick if it's going to be good."

Park's features have a tendency towards comic over-expression, presumably a side-effect of years of showing animators how he wants a character's eyes or face to move. And, while polite to a fault, he's not at ease talking about himself, and it's not hard to guess that he would rather be downstairs in the dark of the studio with his characters than talking about them. Or, indeed, nose deep in a freshly delivered copy of the Beano.

In between his Wallace and Gromit duties, Park has guest-edited the 70th anniversary issue of the comic, published later this month. As he hunches over the edition in his cluttered corner office, it is an achievement that appears to mean as much to him as the Oscars haphazardly displayed around his office - in what appears to be the ultimate accolade, he even features in the concluding frame of the Fred's Bed strip.

"I've been a fan of it all my life. My dream was to draw for the Beano," he enthuses. "When I was 10 years old I started drawing cartoon strips with the Beano in mind. I lived in that world. You own a comic, it's yours and adults don't understand it. You could pile them up under the bed and if you were off school ill, you'd go through them all."

And with that, Park is off into a halting reverie about growing up in 1960s Preston, "where everything looked like it was still from the 1950s". About spending the whole of Christmas Day in 1971 sitting in a box reading his new Beano album, hurtling down side streets on homemade go-karts or "trolleys", dreaming up Wallace-style inventions with his brothers, and spending hours in the heat of his parent's loft working on his animations with his mother's home movie camera.

It was Dennis the Menace, The Bash Street Kids and Lord Snooty that inspired him to pick up a pen, as he lovingly copied out their adventures. And there are clear parallels between the world inhabited by Wallace and Gromit - warmly nostalgic and located somewhere between the 1940s and the present, yet somehow timeless - and that contained between the covers of his beloved Beano.

"It's a bit like the way Ealing comedies have influenced our work here. The surburbness of it and the Britishness of it," he muses. "There's a certain quirkiness. The way Dandy set a cowboy in a strange northern town. There's a slightly bizarre incongruity to it. The Curse of the Were-Rabbit was a Universal horror movie set in the north of England."

Aardman's Bristol base does indeed feel a long way from the bright lights of Hollywood, or even the gossip and bustle of the London media world. As Park itches to disappear downstairs, back on to the production floor, it's easy to imagine that the distance between his parent's loft and Aardman HQ is not so great. "It's what I love. As I get on and films take four years to complete, I tend to have a hankering for very short projects so you can move on to the next idea. It's the ideas I'm interested in. What comes out of your head."

The company was for a time the poster child for the British film industry, with Park's grin and comedy bow ties lighting up several otherwise dull Oscar nights. But it has also had its disappointments in its 36-year history, which takes in Morph, Creature Comforts, Shaun the Sheep and a slew of advertising work.

There was the fire that destroyed decades worth of drawings, and several points where intermittent work caused cashflow problems, or large-scale projects were started only to founder. But with another new commission for a CBeebies Shaun the Sheep spin-off (called Timmy) also in the bag, and its relationship with Hollywood clearer, Aardman seems set fair.

"We never know how long it's going to last. We keep going through darker times and then Shaun the Sheep will take off or something else will turn up," Park says - although he is less optimistic about British animation as a whole, which he fears "seems to be at a low ebb".

Park is back to eyeing the Beano on the desk between us with a mixture of pride and incredulity. "There is nothing like it. It's a one-off quirky thing that has come out of a certain culture. There's a lot of quirkiness, creativity and imagination." He is talking about the comic but he could, of course, be describing himself.