After a military build-up ensues between the USA and USSR over Iran, a thermonuclear war ensues. In the industrial city of Sheffield, a pregnant young woman named Ruth Beckett (Karen Meagher) struggles to survive in the aftermath of the atomic bomb.

At times Mick Jackson’s 1984 film Threads feels less like something you recommend and more like something you warn people about. It is a made-for-television film that scrupulously plays out the after-effects of a thermonuclear war between the USA and the USSR, as experienced by two middle-class families in Sheffield. While not particularly graphic in its presentation – this was, after all, the BBC – it is frankly expressed and pulls no punches. Anyone under the age of 30 who wants to know why Generation X was so cynical should watch this to see how everyone of that generation expected their futures to turn out. Everyone in the 1980s lived in fear of nuclear warfare. Threads is one of the most effective expressions of that fear ever made.

The film blends drama and faux documentary via a dry, almost clinical, voice-over, and the clever use of still photography. The treatment of the material, which is deliberately matter-of-fact and meticulously presented, actually enhances the level of horror. Destruction, firestorms, radiation burns and sickness, economic and social collapse all play out in a serious and mechanical fashion. Nothing is sensationalised. Nothing is unrealistic. It is all horrible.

In many respects this was a perfect project for the BBC, which spent much of the 20th century producing television drama on a thrifty budget. Nothing is wasted, and there is no avenue for lavish, Hollywood-styled presentations. Everything feels remarkably banal and ordinary before and even after the bomb lands. Grey civil servants argue and chain-smoke in bunkers. Individual residents make almost laughable preparations for the impending apocalypse – as if painting walls white and leaning mattresses against them is a suitable defence for a nuclear explosion.

The film’s performances are deliberately understated, and the characters remarkably ordinary. Protagonist Ruth (Karen Meagher) has just fallen pregnant to her boyfriend Jimmy (Reece Dinsdale), and together they have decided to get engaged. Early scenes introduce their respective parents, all effectively as set-up for the audience to follow their stories when disaster strikes. The scope is aggressively personal. There are no scenes of arguing diplomats or military leaders. It simply follows ordinary people as they navigate something unimaginable. It can be difficult through which to sit, and regularly confronting, but also packed with dread and strong emotional effect. It is not simply a powerful film, but an important one too.

Threads was preceded in 1965 by Peter Watkins’ The War Game, a 44-minute faux-documentary on the same subject matter that was perceived at the time as too controversial to broadcast. It is a matter of documented fact that the existence of the earlier work inspired the BBC’s director-general to commission the latter one. Both are superb, and complement one another well – although it would make for one hell of a depressing double-bill.