Some years ago, at a friend’s house, I watched a home video double bill of Se7en and Shawshank Redemption. Both fine films in their very different ways. And what’s inescapably noticeable when you see them back to back like that is the endings, both of which present Morgan Freeman carrying a box with mysterious contents.

Take a step back, and it’s like there’s a third Morgan Freeman, offering the protagonists of both films a choice of which box to open, like a particularly daemonic Noel Edmonds. ‘Now which will it be: your wife’s head, or a stack of cash? Choose carefully.’

That particular sequence could work well in what passes for much of contemporary horror, combining as it does the banal torture antics of Saw, Hostel, etc, and a game show twist that could pass for Lottery satire.

The best horror films often have a strong element of social comment. Torture porn doesn’t begin to qualify unless you buy the argument that it comments on what Americans are getting up to at Guantanamo Bay and with rendition flights etc, which frankly I don’t buy. The films reflect what’s happening there, perhaps, but there’s no sense of analysis or irony or distaste: it’s a mere two-dimensional presentation of people being eviscerated, no nuance at all.

Perhaps you need to monsters and mutants for metaphors to really come alive. There’s no shortage of motifs to play with if you’re looking at vampires, which connect Freud’s biggies of sex and death in one toothy package, and provide rich material about blood, sex, and AIDS. And I don’t know how many times Invasion of the Body Snatchers has been retold now, but it can be (I’m overlooking the lousy Nicole Kidman and Daniel Craig version) a potent way of exploring themes of social conformity, emotional sterility, and more.

But the big daddies of the metaphorical horror film have to be zombies. Under George Romero’s sure guidance, zombie films have become some of the finest satires of our times. They’re a wonderful means of criticising capitalism, proof positive that death is no obstacle to continued consumption. They’re a shambling version of what the Buddhists call hungry ghosts: creatures with immense appetites and stomachs the size of blimps, but with mere pinprick-sized mouths. That’s what they’re attempting to do when they push shopping trolleys round supermarkets in their early appearance. Later, in Land of the Dead, they take on another aspect: migrant workers beating at the walls of the gated communities of the privileged. I haven’t yet seen Diaries of the Dead but I’m betting there’s plenty of room for comment on the modern media with people attempting to make a zombie film while actual zombies attack them. Media eats itself as surely as a zombie snacking on your kneecap.

Given the opportunity, I’d love to do a zombie film that taps into tabloid fears about East European migration. The story would start off with urban rumours and scare stories, but people would soon adjust to the walking dead in their midst. After all, cheap labour is cheap labour, and the food issue could be dealt with by giving the zombies ASBO teens to devour, proving once again that in a good horror film, humans are the monsters.