Think of the film A Private Function (free with The Times today) and what first comes to mind is not a gleefully Machiavellian Maggie Smith, social climbing her way up through postwar Yorkshire. Nor is it Michael Palin’s diffident chiropodist, scorned by his neighbours for practising a rather demeaning kind of medicine. Nor even Alan Bennett’s screenplay, an affably English whimsy that went straight to the hearts of the audience in mid-Eighties Britain. Think of A Private Function and what first comes to mind is the pig.

The reactions of the film’s characters to the porcine star are symptomatic of what seems to be cinema’s special relationship with the pig. A shallow, avaricious woman, Smith’s eyes twinkle beadily with desire as she mentally scrolls through recipes for herbed roast pork, while sweet-natured Palin gets all maudlin and sentimental over the beast. He talks to it and frets over its digestive irregularities. The pig is the beating heart of the film, whose characters are judged by the empathy they show it.

Cinema loves a good pig. Hence the success of the Babe films, the stories of the little pig that bucked the system — the system being the route from farmyard to plate. Babe was an innocent; pure of spirit and full of joie de pig. He won over sheep, duck, dog and man and bought himself a stay of execution.

In the German children’s movie Rudi the Racing Pig, a family prefer to be thrown out of their flat rather than part with the pig they won in a raffle. In The Hour of the Pig, Colin Firth is called upon to act as the legal representation for a pig that has been accused of murder. This is tremendously silly of course, as no pig would do such a thing.

In the world of animation, pigs provided an early challenge to the rodent hegemony. Porky the Pig was Warner Bros’ first cartoon star — and an unlikely one at that. Stuttering, sweating, earnest and well-meaning, he was Everypig, who counterbalanced the lunatic excesses of those he was paired with, most notably Daffy the sociopathic Duck. Porky was the good-hearted naïf, the guileless straight man.

Pigs are natural comedians. Need a comedy interlude? Stage a pig riding competition (the Coen Brothers’ The Man Who Wasn’t There); cut to a pig eating a car (Emir Kusterica’s Black Cat, White Cat) or let drunken piglets run riot (F. W. Murnau’s Sunrise).

Pig goodwill is such that some cunning film-makers have cynically tried to tap into it. Scandalously, the Korean film The Day a Pig Fell into the Well has neither pigs nor wells.

But how did the pig get such a good press? After all, doesn’t the representation of pigness in modern cinema seem rather counterintuitive when we compare it with the way we commonly perceive the animal? With a reputation for poor personal hygiene and gluttony, the pig is a ready-made playground insult — one only has to think of Elton John’s hissy fit at photographers at Taipei airport to realise how effective a term it is at conveying utter distaste.

Perhaps we see ourselves in pigs. They are, after all, meant to be the most intelligent of farmyard animals. And their sins — the gluttony and the sloth that is, rather than the rolling around in dung — are our sins. Or perhaps it just boils down to sympathy for a tough break. There’s a certain crushing inevitability about a pig’s fate. Maybe the cinematic sympathy for the unfortunate pig is just a way of assuaging our collective guilt over a lifetime of bacon sandwiches. Traditionally, we love the underdog — or underpig.

It’s interesting to compare pigs with cats in cinema. We live with Puss and would never consider slapping a slice of him under a grill. Yet cats are universally despised in films, invariably portrayed as cowardly, treacherous, misanthropic despots. We can’t shake off the suspicion that while cats owe us something, the debt runs the other way with pigs.

Which is why, when a pig hits a lucky streak, we will stand and cheer. Can you imagine any interest in the Tamworth Two if the famous abattoir escapers had been sheep or a pair of renegade trout on the run from the fish farm? Conversely, can you ever imagine giving up crispy bacon? Thought not.