ON an industrial estate near Glasgow Airport, a ferocious battle is unfolding. There is a deafening crash as sparks fly and the acrid smell of sheared metal fills the air. Out in the arena, two robots are locked in deadly combat as a baying crowd roars its approval.

It is a gladiatorial scene which feels akin to wandering into a post-apocalyptic wasteland where the machines have taken over and only the strongest will survive.

Welcome to Robot Wars. The cult BBC television series is back after a 12-year hiatus and this time around it is bigger, badder and even more brutal.

The premise is simple: teams of amateur robot enthusiasts pit their homemade creations against each other in the hope of being crowned 2016 champion.

They must not only outmanoeuvre each other, but also a fearsome quartet of “house robots” while surviving a series of hazards that include fire and spikes. Battles are judged on aggression, damage and control.

Backstage the tension is palpable. Tucked behind a curtain is the “dressing room” for four menacing beasts: the house robots. Final preparations are being made to Sir Killalot (a colossal brute with rotating drill lance and terrifying skull face) and Shunt (a plough armed with a titanium axe).

Stablemates Dead Metal (pincers and a whirring circular saw) and the deceivingly sweet-sounding Matilda (pneumatic flipping tusks) are already being wheeled out ready for the next bout.

These are seriously pimped and upgraded models that dwarf the original house robots which viewers would have seen in past series – a necessity to keep up with advances in robotics technology and mechanical engineering.

“If any of the old house robots went in there now they would be flattened,” explains Andrew Robertson, executive producer at Mentorn Scotland which makes Robot Wars for BBC Two. “They wouldn’t stand a chance. It would be over within seconds.”

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In the pits, there is a heady mix of perspiration, passion and pride as 40 teams make last minute alterations with soldering irons or tinker with circuit boards. Their inventions have kooky names such as Kan-Opener, Thor, Gabriel, Glitterbomb and Kill-E-Crank-E.

Since the show was last on air, its die-hard aficionados haven’t rested on their laurels. “After Robot Wars finished it was almost like bareknuckle boxing and went underground,” says Robertson. “The robots have continued evolving. People look to the past and say: ‘How do I beat that?’”

An electric atmosphere is building around the vast, purpose-built arena as spectators wield giant foam fingers and hold aloft laminated posters of their favourite bots. There are pulsating lights and throbbing music. The roboteers wave like gods from the control box.

Goosebumps rise as the clock counts down. 3-2-1 … Activate! The robots come together like prize fighters as they attempt to flip, crush or rip their opponent to shreds.

In the ensuing fray, Dead Metal – no lightweight at 343kg (that’s 54 stones in old money) – is tipped over with a sickening crunch. Matilda rapidly follows suit. It is a modern day David and Goliath moment as the felled giants lie flailing helplessly like upturned beetles.

The 340-strong audience gasps in shock. “Two house robots on their backsides here in the arena,” intones the announcer. “I have never seen anything like it …”

The crowd cheers and jeers. Casualties are wheeled out. Then we’re onto the next match. There’s some trash talk. The doors hiss shut sealing the robots behind double layered polycarbonate bulletproof glass that protects the spectators from any airborne shards of twisted and jagged metal.

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A robot unleashes a high velocity spinning blade as the audience oohs and aahs in awestruck bliss. Its opponent has a powerful-looking flipper device. A series of violent clashes follow to delirious chants of “Fight! Fight! Fight!”

The gaping chasm of the Pit of Oblivion looms, while in two corners the house robots lurk ominously. Searing flames leap through grills in the floor. In the end, the stench of dead robot stings the nostrils. Who emerged victorious? Well, you’ll need to watch the six-part series for that …

The iconic man-versus-machine battle show has certainly come a long way from its original incarnation. Former Top Gear presenter Jeremy Clarkson hosted the debut series in 1998 before Red Dwarf star Craig Charles took over for the remainder of run until 2004.

The rebooted Robot Wars is fronted by Dara O’Briain and Angela Scanlon, while the judging panel comprises Dr Lucy Rogers, Professor Noel Sharkey and Professor Sethu Vijayakumar – all respected academics in their fields of mechanical engineering and robotics.

While Vijayakumar (a world-renowned roboticist based at the University of Edinburgh) and Rogers (a mechanical engineering expert) are both new to the show, Sharkey (professor of artificial intelligence and robotics at Sheffield University) has appeared on every series of Robot Wars.

He has watched it grow from grassroots to international phenomenon. “In Robot Wars the evolution was fantastic,” says Sharkey. “In the first series I was sitting on the wall with my feet inside the arena while they were fighting, but by series three we had to hide under our desks.”

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Yet, the stars of the show are undoubtedly the house robots. They even have their own entry music: Sir Killalot rolls into the arena to Motorhead’s Ace of Spades, while Thunderstruck by AC/DC announces the imminent arrival of Shunt.

Their stats are reeled off like world class athletes: Shunt weighs in at 327kg and takes only 0.25 seconds to operate its CO2-powered titanium axe, while Sir Killalot tips the scales at 741kg and possesses hydraulic claws with 2.5 tonnes of crush force. Matilda can zip along at 14mph.

It is kitsch and geeky and gloriously nostalgic. Sitting in the audience, I’m instantly transported back to my student days when being sprawled on the sofa watching Robot Wars regularly provided much-needed respite to a cheap beer-induced hangover.

The show garnered a peak audience of six million viewers in its heyday during the late 1990s, with the format going on to become a global success shown in 45 countries including the US, Australia, Canada, China, India, Germany and Italy.

Charles won a raft of fans for a reverent presenting style that his predecessor Clarkson lacked. His successors O’Briain and Scanlon are aware that they have some big shoes to fill.

“I don’t think there is anyone who wasn’t aware of Robot Wars and the cult around it,” says Scanlon, who is a regular film presenter on The One Show and co-hosted live coverage of T in the Park. “The fans never went away. They didn’t forget about the show and it feels like it has lived on.”

Many of the new batch of contestants were viewers in their teens when the original show aired. Others are veterans that have featured in the past and returning for another shot at glory.

“There is a father and daughter team and the girl was a Robot Wars baby,” says Scanlon. “Her mum went into labour while watching her husband fight. She is back with her dad and his old team-mate. She is a ballerina but also into robots. It is kind of heart-warming and totally bonkers.”

Despite the fierce competitive nature, there is a camaraderie among the amateur roboteers. “In one fight a robot got destroyed – taken apart bit by bit – and there were fragments everywhere,” says O’Briain, who also hosts panel show Mock The Week.

“Later there were four or five different teams gathered around one table, welding pieces back together, to help get it out to fight again.”

Although it’s not all gooey marshmallow moments as Scanlon is quick to point out. “That community aspect is sweet, but you talk to them in the pits as they are getting ready and the most wonderful people turn evil in the flip of a switch,” she says. “There are very few formats that allow for people to talk about pounding and killing with such enthusiasm.”

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O’Briain nods in agreement. “I think it’s about metal on metal,” he says. “The fact there is a human part to it is great because there is a lovely back story to it all, but then they go into a closed-off arena surrounded by two layers of bulletproof glass with the pure intention to destroy each other. The sheer kinetic energy and noise of these things smashing into each other.

“They have spinners, these arms that go round at 3,000 revs per minute. Those can do proper damage and sheer off things. The number of times we’ve had things smash into the glass in front of us. Huge lumps of metal. You can see it just below you, the steam rising off it, shrapnel basically.”

The duo admit to rooting for the underdog and a soft spot for some of the more flamboyant-looking robots. “One had an incredibly ornate broad sword the first couple of times it fought,” says O’Briain. “It was astonishing to watch. This thing loped around like an emu with a sword for a head. The show has moved on from the robots that are simply utilitarian.”

Beside him, Scanlon takes up the story. “It absolutely demolished the other robot but with beautiful elegance,” she adds. “For people at home watching with their children and thinking: ‘we should totally do that’, seeing things that look like they have been thrown together with whatever is chucked in the garden shed is quite encouraging. It makes it feel more inclusive.”

Outside in the pits, Ellis Ware, 20, from Shropshire is fiddling with four monster-sized batteries on a robot called Pulsar. “From concept to actually being here fighting was only nine weeks – it was a tall ask,” he says. “I have been working round the clock to get it ready.”

Does he spend a lot of time thinking about robots then? “Ever so slightly,” he laughs. “For as long as I can remember. From being a three-year-old watching the original show until now, it is something I have always wanted to do. It is a dream come true to be on Robot Wars.”

Ware says his love of building machines is one which spans several family generations. “My grandparents were engineers. It has always been in my blood,” he says. “I have made things for as long as I can remember. I built my first fighting robot in 2012.”

At a nearby table is Gary Cairns, 28, from Mintlaw, Aberdeenshire, who is team captain for PP3D Robotics. Cairns was previously involved in Team Typhoon – which won series seven of Robot Wars – as a teenager.

He gained a masters in mechanical engineering from Strathclyde University and became a drilling engineer for BP before setting up his own 3D printing company last year.

“I have real history with Robot Wars,” he says. “All the way through university I was still involved in the live events circuit. I have watched Robot Wars since the very first series. I started out building things from Lego and whatever I could get my hands on. I was always the kid who would take things apart to see how they worked.”

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Cairns estimates he has spent £2,500 to date on designing and building PP3D. “You can easily spend four figures on these machines,” he says. “This one was designed and built in two months. I’ve been working on it full-time with 12 hour days including weekends. It has been tough.”

His team-mates are fiancee Sarah Dennis, 26, a farmer, and their friend Jamie McHarg, 28, a domestic gas engineer. “This is very much Gary’s thing,” says Dennis, with a smile. “He is a force to be reckoned with and sometimes gets a bit carried away. Gary is willing to trash the machine for a good fight, but he has the skill and ability to put it back together.

“Every time he gets better at it and builds a far improved version. I don’t do much other than fix the burns, sew up the stitches and lend moral support. Everyone in our generation is nostalgic for Robot Wars and get a bit excited. It has kudos.”

As for the essence of what makes Robot Wars such addictive viewing, Scanlon perhaps best hits the nail on the head. “You are completely immersed in their world,” she says. “They’ve spent three years building a robot, painstakingly putting it together and it takes three seconds to demolish it in front of everybody. You can’t help but be totally engrossed in that.”

Robot Wars returns to BBC Two, 8pm, on July 24

READ MORE: meet the fearsome Robot Wars stars Sir Killalot, Matilda, Shunt and Dead Metal