Unlikely as it sounds, I send thanks to the ghosts of Mary Whitehouse and Margaret Thatcher. Without them, I might never have become a lover of extreme cinema.

The bouffant duo switched me on to "Video Nasties’" The early 1980s were a free-for-all after the launch of home video. There was no regulation. Cinema certificates didn’t cover what you watched at home.

Britain - ever home to prissy, joyless busybodies - got its knickers twisted over on-screen sex and violence. Horror films were blamed for rising crime. Why would the religious-right worry their middle-class heads about poverty and unemployment when they could start a moral panic?

Thanks to the right-wing press and right-wing politicians, kids like me began to hear about movies which sounded ridiculously cool. If an old grinch like Whitehouse hated something, then we wanted it.

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That same year, dullard DJs and others who loved the idea of banning fun, started hating on Relax by Frankie Goes to Hollywood - making it one of the biggest singles of the decade.

Tell kids something is bad, and rest assured they’ll go nuts for it. Thus, one Saturday in February 1984 - I’d just turned 14, and the Video Nasty ban was still a few months away - me and my mates went to the local video library (ask your parents if you’re under 30).

I wanted a specific title: The Texas Chain Saw Massacre. Mum and dad were out. I had an empty. It was the 80s. Parents were never around. GenXers were called "Latchkey Kids" for a reason.

In every brain-dead tabloid rant, Texas - as aficionados call the film - was top of the confected hate-list. It was decadent, depraved, likely to corrupt young minds. Bring it on, we thought!

Back home, I fired up the Betamax player - my parents were never the brightest with technology, forsaking the much better, more popular, VHS version of home video.

From the opening moments, with its title card claiming the events in the film were real (they weren’t, but director Tobe Hooper was a genius and knew a sense of authenticity would freak his audience out even more), to the last mad reel, I was spellbound and horrified in equal measure.

This month Texas turns 50. It’s never lost its power. There will be many readers who haven’t watched this film. Thanks to all that bull back in the 1980s from Whitehouse and Co, the notion was fixed in millions of minds that Texas was some worthless piece of blood-splattered trash.

Needless to say these barbarians hadn’t watched the film. What’s changed, you might ask? There’s millions of idiots today who screech for books, films and TV shows to be banned simply because they don’t like what they’ve read. I’m only half-joking when I say that anyone this stupid probably shouldn’t be trusted to vote.

Texas is indeed horrifying, but it’s also a sophisticated, technically elegant, art-house movie - a cinematic masterpiece. Indeed, there’s little blood in the entire 83 minutes. I went to school the following Monday raving about how boggled my brain was by the gouts of gore everywhere.

But I’d fallen for the tricks Hooper played on his audience. The sense of dread he establishes is so overpowering that when violence comes the viewer imagines blood splashed across screen.

Rather, Hooper shoots his film in such a staccato aggressive style, creating such a mood of suffocating nightmare, that we feel we’re drenched in blood. While there’s considerable - and shocking - violence, the horror is primarily psychological. In tone, it’s much more black, than red.

Texas revolutionised the horror movie even more profoundly than Alfred Hitchcock’s Psycho. Hooper perfected the "final girl" trope, where the female lead becomes the main protagonist, enduring and - mostly, though not always - surviving to defeat the villain.

Marilyn Burns as Sally Hardesty becomes the foundational "final girl’" In that sense, Texas was distinctly feminist for its time. Sally doesn’t need some guy to save her. The guys die. She’s not Marion Crane (Psycho’s Janet Leigh), killed off just as the film gets going and lacking any real agency of her own. Sally has guts and brains.

She also has a disabled brother, Franklin. It wasn’t often you saw disabled characters in movies back then. However, it’s the "baddies" who scorch your consciousness. Sally and her friends are travelling across Texas, they park up one afternoon and find themselves near a ramshackle old house.

Leatherface, played by Gunnar HansenLeatherface, played by Gunnar Hansen (Image: Commercial/PR) A family of serial killers live in there, including the monstrous - and pitiable - Leatherface (played by Gunnar Hansen), based on real-life necrophile murderer Ed Gein, who made clothes from corpses. We’re in truly weird, deeply messed-up, territory.

But it’s that kernel of truth which makes Texas so powerful. Back then, Ian Brady and Myra Hindley still haunted children. Texas tells us: the real monsters aren’t vampires or zombies, but other people.

However, Texas isn’t a masterpiece simply for its sense of inescapable, overwhelming terror. It remains a brutal critique of the American Dream. The events take place in a "White House".

The inhabitants of this American microcosm are impoverished - financially and morally. "The Family", as they’re known (note the allusion to the Manson Gang) are capitalism’s victims, debased - stunted - by their own society, reduced to eating fellow humans. Isn’t dog-eat-dog capitalism the very definition of cannibalism?

There’s no rule, nor order, in Texas - a very post-Vietnam, post-Watergate sensibility. The movie is also an indictment of cruelty, not a celebration. Nobody - not even 14-year-old me - watched this film and relished the violence. We watched it and thought: what are humans capable of?

And what are we capable of? The film still asks that question. Texas emerged amid social, political and global violence. Plus ça change, plus c’est la même chose.

Texas should be celebrated as one of the greatest films - not just horror films - of all time. I won’t urge anyone to watch it who’s of a nervous disposition. It won’t do much for your dreams. But if you’ve never seen it, and think you can handle it, then try this film.

What you’ll see is an artwork that at 50 still has the power to emotionally floor an audience and say something profound about the world in which we live.

Neil Mackay is the Herald’s Writer at Large. He’s a multi-award-winning investigative journalist, author of both fiction and non-fiction, and a filmmaker and broadcaster. He specialises in intelligence, security, crime, social affairs, culture commentary, and foreign and domestic politics.