If your world view is formed by the Evening Standard, Daily Mail or Metro; if you think travelling means going where the Tube doesn't; and if you think that you can sort good people from bad by the money they earn: this is a horror film that'll be right up your gravel path.

West London primary school teacher Jenny and her boyfriend Steve seek to escape the hustle and bustle of the City for a weekend by taking a trip to the wilds north of Watford, possibly Nottinghamshire given the locals' accents, and specifically to an area fenced off to the public by developers, called Eden Lake.

Their little picnic relaxing on the shore, however, is disturbed by trespassers of a much worse sort - youths, several of them (including actor Thomas Turgoose who has a great future) all in trackies and trainers, and with a great big dog to boot. Said youths predictably make trouble with our perfectly respectable young couple, and before long, they're drawn headlong into the world of dangerous dogs, knife crime and happy-slapping, exactly the kind of perils that their economic status in life had previously protected them from.

And if you share the couple's background, that's how the film works. There's nothing quite so savage and repellent as an unfettered working class who, quite naturally in the absence of authority in that secluded oasis away from mobile phone reception, will revert to savagery in pursuit of bloodthirsty aims.

For those of us in the real world, however, it's too insulting to take seriously. While the sadistic gore and horror means you're never quite going to take the side of the chavs, the victims never quite elicit the sympathy the film wants you to have for whether they live or die. Also, as someone who has moved to Nottinghamshire and quite likes it here, the film fails in that I don't find the residents here as savage and hillbillyish as I'm asked to believe.

The easy thing to say about a bad film is that the ending is the best part. In fact, many doo-yooers have sought to criticise it. I won't spoil it, but I think it was probably the brave way to go, particularly after what had gone before. Overall, it was a high point to a film I largely disliked.