p>The most unusual thing about this thriller is that it exists at all. The situation in Northern Ireland was so tense, fraught and full of horror that an accurate, clear-sighted telling of it has been almost impossible to do. Steve McQueen’s “Hunger” — which many critics loved but this one loathed, did open the doors for a more visceral type of discussion about the Troubles — in the focus on the minds and bodies instead of the politics of the relevant people. Written by a Scot (Gregory Burke), funded with British money and directed by a French-Algerian (Yann Demange), “ ’71” has no apparent interest in sectarian propaganda of any kind. Any of these things is extremely unusual; but the combination is, until now, unheard of. And the result is one of the sharpest British movies in some time.