Dir:

Yann Demange

With: Jack O'Connell, Sean Harris, Sam Reid

Runtime: 99 minutes

THOUGH it deals with British history, this exhilarating Belfast-set chase thriller has an air of fresh out of the box newness about it.

Front of camera, the characters are newly trained British soldiers being deployed to Northern Ireland as the 1970s begin and peace is unravelling.

Behind the camera are Gregory Burke, the Scots writer of the play Black Watch, here watching his first screenplay arrive on the screen, and Yann Demange, making his feature film debut after a career in television that has included Top Boy and Secret Diary of a Call Girl.

All of this relative inexperience turns out to be both a benefit and a drawback. Demange and Burke have concocted a movie bursting with ambition. That this co-production by Creative Scotland and Screen Yorkshire ends up overreaching itself is not a major sin. Would that other British film-making dared to do the same. But it does mean that, in its latter stages especially, '71 comes across as a tale pumped full of steroids when a leaner, more focused approach would have done the job more effectively.

There is one member of the cast and crew who, young as he is, already seems like a screen veteran, such is the calibre and impact of his performances. Jack O'Connell, lately of Skins, Starred Up and 300: Rise of an Empire plays Gary, one of the newbies told they are going to Northern Ireland and not Germany.

"You are not leaving this country," the lads are informed. Yet when they arrive in Belfast it feels as if they have landed not in a foreign land but on another planet.

Through a series of deft keystrokes, Burke makes it plain who these boys are: the kind of working class lads who have always been the backbone of the British Army, all with their different reasons for joining up. In Gary's case, he has enlisted straight from the care home.

As tough as their upbringings have been, none is quite prepared for what awaits. For once, having a budget that is a fraction of what Hollywood would deploy is no drawback. Rows of empty terraced houses, streets littered with burning cars, wastelands: broken Britain can still supply these at low or no charge.

Led by an officer just as soaked behind the ears as they are, the patrol ends up in a confrontation with locals, at the end of which Gary finds himself separated from his mates. Now he has a new mission: get back to the barracks. But between him and safety are men who want to kill or capture him, and not all of them are the enemies one would expect.

Like all the best ideas, it is a simple one, and one made for the movies. Put a character in peril and make him or her run for their life, throwing obstacles in the way at every turn. Burke and Demange further up the ante by setting the action at night, when everything seems worse, and in a housing estate with lots of places to hide and seek.

The help and hindrances placed in Gary's way are many and varied. The film has a sure touch when it comes to getting across what a dirty war the conflict in Northern Ireland would turn out to be. In this grim house of mirrors, nothing was ever quite as it seemed.

Though the dialogue takes the occasional lurch into cliche - even the dogs in the street seem to bark "we are at war" - on the whole it is spare and convincing.

Certain characters, too, fall into the two-dimensional category, including the posh officer and the weasel-faced intelligence agent, but by and large this is a bunch to believe in and care about.

If the film ends up chancing its arm and straining our credulity once too often, O'Connell is never less than spot on in all he does.

When he sweats, we sweat. When he hurts, we hurt. Be it in 1971 or seven days ago, he is outstanding as an ordinary hero for the age.