There’s no two ways about it; Neds is a tough movie to watch. How tough? Well, let’s see.

Neds — which we’re to understand stands for Non Educated Delinquents — follows John McGill (an outstanding performance from Conor McCarron) who has so far managed to flourish intellectually in the shadow of an alcoholic father, a thuggish brother and the uncompromising environment of a Glasgow housing estate in the 1970s. On the final day of Primary School, he picks up a top pupil award and then runs into a random bully who explains, in colourful terms, exactly how many strips John will be torn into when he gets to the big school. At this point, a mere four or five minutes in, we’ve had more Fs and Cs than you’d find in your average Scrabble tournament and the Tough-o-meter is pretty much screaming off the scale.

If nothing else, director Peter Mullen (The Magdalen Sisters) knows his source material. The Glasgow of the 70s is so accurately portrayed and witnessed through a hazy, almost out of focus lens, you could be forgiven for thinking the film is actually 40 years old. The lexicon, while exceedingly swearmungous, is authentic. And it’s the little touches — the charity dog outside the chemist, the old crisp wrappers, the giddy height of the hem on the jeans — that really cement the viewer in this timeframe. Continuity-wise, and in stark contrast with the troubled youths portrayed, the film doesn’t put a foot wrong.

So it’s with a loving eye that we follow John on his inevitable descent from gifted pupil to violent gang member and it’s here that the film manages to be a stunning revelation and slight disappointment, all in the one breath. McCarron is utterly spellbinding in the lead role and conveys naïvety, vulnerability, mania, rage so efficiently and sometimes with little more than an arched eyebrow or a scowl. However, the fact that the young lad can go from protégé to violent gang member within the space of six weeks seems a stretch and given that this is a pivotal moment, it does tend to taint the scenes that follow, even when the matter is addressed full on in a charged Latin class led by Steven Robertson (The Tourist).

The largely unknown supporting cast are equally at home with the heavy dialogue, even if they aren’t asked to cope with as much in the way of a narrative arc as McCarron, and the young lad who plays the bespectacled Wee T provides some uneasy comic relief. Oddly, it’s Peter Mullen’s performance as John’s alcoholic dad that really misses a beat as he tries to cram every Glaswegian stereotype behind his NHS glasses and tatty suit jacket.

Mullen — who also wrote the script and probably made the tea and swept up afterwards — is wise enough to offer little in the way of redemption for John. To do otherwise would betray the real John McGills out there but the movie’s close, in the middle of a safari park, manages to be both poignant and significant even if the audience — battered and bruised from the preceding two hours — is left with the sense that any optimism will surely be temporary.

So tough. Yes, without a doubt. It’s a flinching, look-away sort of experience but as worthwhile as Scum or Trainspotting and an unsettling reminder of inner city life in Scotland not so long ago.