Quite whether Mum & Dad, the low budget debut feature from Steven Sheil, is the best British horror film in years or The Texas Chain Saw Massacre given a sleazy torture porn makeover is already a matter of critical debate. In favour of argument #1 is that it takes us to some pretty dark places, stomps cheerfully over the taste barrier, and is at times quite tense and even uncomfortable to watch. Countering this is its unrelenting emphasis on the emotional and physical suffering of the unfortunate female victim at its centre, an ordeal that lasts for most of the film's 84 minute running time.

It kicks off in deceptively humdrum fashion, with young Polish immigrant cleaner Lena trading chat with her English colleague Birdie as they go about their business in an office complex close to Heathrow airport. When Lena misses the last bus home, an event that appears to have been engineered by her workmate, she is invited by Birdie and her silent step-brother Elbie to spend the night at their nearby family home. She's not long through the door, though, when she's knocked unconscious and has a hypodermic needle thrust into her throat. She wakes to find herself tied to a bed and her vocal chords paralysed, a prisoner of a clearly demented middle-aged couple known only as Mum and Dad. Mum coos over her and calls her 'angel', but derives an almost sexual pleasure from piercing her skin with spikes and taking a scalpel to her back, arms and legs. It's best she doesn't protest, though, or she'll be dealt with by Dad, who when Lena first awakes is in the process of dismembering another, still conscious unfortunate in the next room.

What immediately separates Mum & Dad from its Texas Chain Saw roots is the everyday nature of its diabolical family. There's no leather-masked monster or crazed hitchhiker here, but a loving and possessive mother, a sternly authoritative father, a spitefully jealous and manipulative sister, and a shyly repressed brother, all of whom appear to have had a morality bypass – imagine the Royle Family going bugshit and preying on the isolated and the lonely and getting their kicks with hammers and knives and you're halfway there. That Birdie and Elbie have been abused into this lifestyle is something that only vaguely registers as the story progresses.

This does make the subtext somewhat easy to read, one in which overly controlling parents violently abuse the children in their care in a twisted interpretation of family love and loyalty, one that can be passed on to the next generation. It's an exaggeration, perhaps, but one given a degree of unfortunate credence by recent, headline-grabbing cases of note. The film's pre-publicity has also suggested a connection to the crimes of Fred and Rosemary West, a seemingly innocuous couple who were responsible for the rape, torture and murder of at least twelve young women over a twenty year period, and whose crimes were committed behind the doors of ordinary suburban homes.

But Mum & Dad is trading on its horror credentials rather than its social commentary and it wastes no time in establishing them, though does so in a manner that definitely marks it as a film of our time. Where back in the 1970s the sight of a floor strewn with bones and feathers was enough to freak an audience out, now it takes Dad masturbating onto a beef steak as the family watch lovingly on, followed by a close-up of the said steak dripping with... well, you don't need me to elaborate, do you? While this does effectively confirm Dad as a sleazy scumbag, you can't help but suspect the scene is there primarily to ensure there's something that will make even the most hardened horror audience squirm – there's even a follow-up shot the next morning designed to give you a secondary twitch.

The character of the suffering female victim is as old as horror cinema, of course, and placing someone in jeopardy for an extended period has been a favourite wind-up since the genre's early days. But it's the nature and length of Lena's ordeal that could see the film labelled (and dismissed) as torture porn, the latest in a line of low-budget horrors in which young women (and sometimes men) are physically and mentally abused for our queasy entertainment. Whether it's a charge that needs answering will depend very much on your views of this most maligned of modern horror sub-genres, and whether Mum & Dad meets the entry qualifications. On the surface it does, for while director Sheil has quoted amongst his influences Freddie Francis's rarely seen 1968 Mumsy, Nanny, Sonny and Girly and Pete Walker's 1974 Frightmare, shifting the focus from the murderous family to the suffering of a single victim changes the emphasis and makes the experience a more unsettlingly subjective one.

That this makes for difficult viewing in places is no bad thing – horror movies are not meant to be cinematic relaxants after all – but it's that torture porn fondness for realism over fantasy that is likely to send a portion of the audience scurrying. The violence isn't extreme or overloaded, but its up-front establishment as a consequence of disobedience is enough to both keep Lena in line and send some of us on a fingernail chewing marathon when she makes a risky (and at one point nicely grotesque) attempt to alert an outsider, or when she temporarily frees her bonds and goes on a stealthy wander through upstairs rooms. In contrast to the torture porn standard, the scenes in which physical harm is inflicted on Lena are not staged purely for the shock value or perverse enjoyment, but to establish the nature of the threat she is facing and to heighten both our engagement with her as a character and the tension that arises from her desperate quest for survival.

It's down to the performances to sell both the reality and perversity of the piece, and for the most part they deliver. There's a slight but enjoyable theatricality to Dido Miles' portrayal of Mum, as if Morticia Addams had grown up in Albert Square, and if Ainsley Howard's Birdie has that familiar acted teen brat air about her, it doesn't stop you wanting to slap her every time she smugly gets one over on the long-suffering Lena. Perhaps the most interesting casting of all is Perry Benson, a recent recruit to the Shane Meadows troupe and the one whose ordinary bloke looks and delivery most convincingly sell the familial abuse subtext, angrily spitting "Try to show me up in front of my friends, would ya?" to a suitcase-enclosed Lena before beating her repeatedly with a mallet. But the real acting honours here go to Ukrainian actress Olga Fedori, whose terror and pain in the role of Lena is sometimes affectingly real, but whose angry defiance in the climactic Christmas party sees the strength that has kept her alive to this point bubble thrillingly to the surface.

For all its strengths, I still find it hard to vouch for Mum & Dad as a great work of modern horror. The borrowings show (the Texas Chain Saw influence is unmistakable in the final scenes), there are some a couple of serious plausibility holes, and for a portion of its potential audience it's going to play as sleazy torture porn with pretensions to social commentary (the negative and somewhat predictably worded IMDb comments to this effect have already started rolling in). But I'd also argue that it's a considerably better genre work than the more vocal detractors have claimed, and that to criticise a horror film for trying to shock its audience is akin to complaining about the explosions in an action movie. Director Sheil works a few small wonders with his meagre £100,000 budget (the film was made as part of Film London's Microwave project, where that was the maximum permitted expenditure) and convincingly transforms an ordinary family home into a fortress of suburban horror, perversity and twisted family values. For a horror movie made by a horror fan for the like minded, it does pretty much what it says on the tin, but it's also well enough made and with enough neat ideas of its own to bode rather well for Sheil's future genre projects.

Mum & Dad was shot on Sony HD-CAM and employing the P+S Technik Pro35 Image Converter to enhance the sharpness and film look of the image, resulting in an image quality that belies the film's micro-budget. Cinematographer Jonathan Bloom deserves full credit here, working as he was in actual locations rather than a studio and having to light small rooms with minimal resources, no easy task I can assure you. The 1.78:1 anamorphic DVD transfer is generally first rate, boasting a crisp level of detail and rather splendid contrast and colour, and save for a few minor burn-outs on whites, at no time does the image have a video look about it.

The soundtrack is Dolby 2.0 stereo only and has the sort of clarity and range you'd expect from even a low budget modern movie, though separation is only really noticeable on the overused transition shots of planes flying over the house, while the sinister notes that stand in for a traditional score lack the bass wallop a 5.1 mix might have given them.

Mum & Dad is probably unique in that it received a simultaneous release in cinemas, on DVD, on Pay-per-View, and as an internet download, all on Boxing Day 2008. As far as I am aware, only the DVD offers any accompanying extra features. And they are...

Audio Commentary
Director Steven Sheil and producer Lisa Trnovski prove genial hosts for a useful trip through the background of how the project came to be, the difficulties caused by working on a low budget (camera batteries dying, no time to do coverage, having to work in actual locations), on working with the actors, and on some of the themes touched on by the film. There's also some useful stuff in here for anyone thinking of shootiing low-budget projects of their own – if you've been there already then it'll certainly have a familiar ring.

An Interview with Director Steven Sheil (4:09)
This appears to have been grabbed at a festival screening – it doesn't last long but Sheil could talk for Britain at the Olympics, so there's quite a bit of ground covered, only some of which is duplicated by the commentary and...

Frightfest Q&A Session with Cast & Crew (5:52)
Sheil obviously gets asked the same questions each time (Pete Walker's Frightmare gets enough coverage in the extras to provide all the sound bites an enterprising distributor would need to promote a re-release), but he's joined here by actors Perry Benson, Dido Miles and Ainsley Howard, who comment on their roles, and Sheil does suggest that his next movie will also be horror, but with a hopefully higher budget.

Film London Interviews (15:48)
An interesting collection of promo interviews shot by Film London, who tease information about their work on the film from director Steven Sheil, actor Perry Benson, producer Lisa Trnovski, cinematographer Jonathan Bloom, makeup designer Vikki Lawson, production designer Jess Alexander, the intriguingly named special effects supervisor Simon Craze (who enjoyed the improvisational aspect of working low budget) and sound mixer Alex Thompson.

Short Film: Through a Vulture Eye (3:00)
A simple horror short with the sort of twist favoured by student genre works, made by Sheil a few years back (the date is unspecified) in which a killer recalls the act of murder as if he's planning a poetic novel on the subject. Personally I'd rather have seen his 2002 short Cry here, given that this was the film that got Sheil his shot at the London Films Microwave scheme.

Mum & Dad: Behind the Scenes (3:15)
A brief collection of behind the scenes DV grabs, including some larking about by the special effects crew and Perry Benson telling the camera operator to fuck off.

There's also a trailer (1:25) for those who like to recall how these things are sold to us.

Opinion is already very vocally divided on Mum & Dad, a film that has delighted some hardcore horror fans and provoked contempt from those who profess to know better. I appreciate both viewpoints but choose not to agree with either. Yes, it's derivative and self-consciously nasty, but Sheil's desire to create a British equivalent of the American "fucked-up family" horror sub-genre is a worthy one that he does rather well by. It goes without saying that if you're not a genre fan, and I'm talking serious genre fan, then this definitely ain't for you, but if you're game then Revolver's DVD delivers rather well on all fronts.