Nick Park's unassuming duo has been dealing with fame their whole working lives, and it hasn't changed them a bit. Their 1989 debut, A Grand Day Out, was nominated for an Oscar, only to be beaten by Park's other entry, Creature Comforts. In 1993 and 1995, Park walked off with the Best Short Film Oscars for The Wrong Trousers and A Close Shave respectively. But perhaps their greatest success is that no age group, from toddlers to centenarians, is excluded from enjoying their adventures- something television executives shrewdly recognise in their Christmas listings.
So why is the world so in love with Wallace and Gromit? Their innate, unconquerable Britishness must play a part. Wallace, voiced by Park's fellow Lancastrian and Last of the Summer Wine octogenarian Peter Sallis, is a lonely, decent man in a tank-top. He has a fondness for tea and toast and Wensleydale cheese. The whole situation evokes a more innocent time, in a North not yet caricatured by Coronation Street.
And there is so much more to enjoy. Wallace's childlike enthusiasm for inventions and new contraptions is infectious. For Wallace, every morning is a harum-scarum jaunt along a production line of malfunctioning labour-saving devices of his own invention, which are designed to dress and nourish him. More often than not, our hero starts the day with his sweater round his ankles and jam on his face.
But it is Gromit who is the star turn. Mouthless, silent, faithful but disapproving, Gromit is the brains behind the operation. And because he does not speak - he is, after all, a dog - we must learn everything through his facial expressions. What a story those expressions have to tell - imagine Jack Nicholson as a silent movie star and you're somewhere close. But these characters have made their way into our hearts through the strength of their storylines. All three instalments so far have had compelling but offbeat narratives, mixing absurdity and pathos in equal measure. Think of the moon-dwelling robot in A Grand Day Out whose only wish is to ski, or the daring heist executed by the evil penguin in The Wrong Trousers.
The Curse of the Were-Rabbit's story line exemplifies just how brilliant Park's storyboarding is. It's days before the annual Giant Vegetable Competition, and, with their humane pest-control invention, "Anti-Pesto", on the market, Wallace and Gromit are making a packet. The allotment-dwellers of Wallace's home town - which Park recently revealed was modelled on 1950s Wigan - are distraught when a vicious herbivore, the Were-Rabbit, strides into town, determined to terrorise their marrow-patches. The local dignitary, Lady Tottingon, calls in Wallace and Gromit to rid the town of the Were-Rabbit, and mayhem ensues.
What's so special about the story is that the greatest glory in the town where Wallace lives is afforded by "The Golden Carrot" prize for growing the biggest vegetable. Given that saving the planet is normally a modest aim in the average Hollywood blockbuster, such small-town ambition is immediately endearing, and a huge part of Wallace and Gromit's appeal.
Of course, there's always an academic about to ruin everyone's fun and tell us why we're really enjoying something. In this case, it's Brian Clifford, a professor of Psychology, who tells us: "We must realise that when characters like Wallace and Gromit act with freedom and provide a form of disestablishmentarianism, this can only be good for us. Cartoons can be most therapeutic. Nowadays, we are generally under the whip, nose to the grindstone, and animated characters like Wallace and Gromit, who seem to be turning against the system, find a resident audience with their humour, with children or adults.
"Animation is more than a form of escapism. It reflects everyone's desire to be bold enough to turn against authority at some level. Being three dimensional, Wallace and Gromit make the escapism that much more realistic. The idea that the films are for children is a myth - adults find a release in them."
In other words, Wallace and Gromit are funny. But Professor Clifford's point, that these animated characters speak to adults as much as they do to kids, is misplaced. Their appeal has as much to do with the web of film and television references as "everyone's desire to be bold enough to turn against authority". Disparate influences, such as the Ealing comedies and Hitchcock thrillers, are cross-referenced and interspersed into the narrative. Understanding a sophisticated joke in such a simple medium is richly gratifying.
It is striking, too, how many adults are interested in the nuts and bolts of how Wallace and Gromit is made. There is something intriguing, in this rush-rush world, in Park's painstaking method of working, which he calls "claymation". He first started producing moving pictures this way as a young animator, because "all he needed was some Plasticine and an anglepoise lamp". And, despite having an immodest £40m budget for Revenge of the Were-Rabbit, rather than the positively demure sums with which Park had previously produced Wallace and Gromit stories, nothing fundamental to the process has changed.
In the Bristol headquarters of Aardman animations, Park still works with the Plasticine models himself. And, although he now has a large team of helpful animators to assist him, his rate of progress has remained pedestrian - about three seconds of usable film a day.
Actually, when one considers that each frame has to be set up individually, often with a number of characters, and that there are 24 frames per second of film, it doesn't seem so bad. But tell that to Jeffrey Katzenberg, the Dreamworks boss and Park's American paymaster. He has travelled across to Bristol every 10 weeks during filming, and has spoken to Park on the telephone every day, just to check on progress.
Katzenberg's attentions, though, have not worried Park unduly. The Curse of the Were-Rabbit has taken five years from storyboard to premiere, a time scale which would normally be unthinkable for a Hollywood feature. "[He] always knew about the way we worked and how long these things take," said an unapologetic Park in a recent interview. I hope it's not anti-American to say that I take immense personal pleasure in the story of a single, middle-aged British eccentric frustrating the might of the American studio system.
From their on-screen personas to their off-screen battles, Wallace and Gromit are little guys helping to make their world a better place. We love them because we love an underdog story. We love them because they make us laugh more than it is natural to laugh at six inch plasticine models. And we love them because sometimes it is just possible to see the thumbprint of their dotty creator smudged across their brows.