IN AN industrial estate on the outskirts of Cumbernauld, a mesmerising scene is unfolding. Within a cavernous warehouse lies a kaleidoscope of Parisian grandeur complete with lavishly furnished salons, parlours and boudoirs bedecked in expensive-looking finery.

Throughout the hangar-like space is a hubbub of activity. Crew and extras mill around. Efficient-looking types with headsets and clipboards bustle past. In the canteen, actors dressed as French soldiers relax between takes, drinking tea and eating custard creams.

It is here that the hit US television series Outlander is filmed. The second season will see the rugged backdrop of the Highlands temporarily replaced by the opulence of 18th-century France as an ambitious plotline to alter the course of history unfolds.

Sony Pictures Television, which makes Outlander, films the series on location across Scotland with many of the interiors shot at Wardpark Studios in Cumbernauld, a former factory that has been converted into a production base and four state-of-the-art sound stages.

Such has been the success of the facility, the Scottish Government recently lent its support to multi-million pound expansion plans to turn it into the country’s first permanent film studio.

Testament to Outlander’s soaring global popularity, it is an international group that has joined me on the journey up the M80 from Glasgow – journalists who have travelled from as far afield as Japan, Canada, the US, Germany, Spain and the Netherlands. Yet, ironically, despite the series being made in Scotland, it continues to fly largely under the radar here.

Based on the bestselling books of Diana Gabaldon, Outlander charts the adventures of Claire Randall who, during a second honeymoon to Scotland with her husband Frank in 1945, is transported back to 1743 through a mysterious set of standing stones. It is there, on the brink of the last Jacobite rising, she meets dashing Highlander Jamie Fraser and a powerful love story begins.

Gabaldon drew inspiration from another time-travelling series: Doctor Who. In an episode from the late 1960s, Patrick Troughton encountered a Scotsman from 1745. The young man was wearing a kilt, which the Outlander creator thought was “rather fetching”. The first novel was published in 1991 and the eight-book series has since sold more than 26 million copies.

The latest instalment is adapted from her second book Dragonfly in Amber. It sees Jamie and Claire – played by Dumfries and Galloway-born Sam Heughan and Irish actor Caitriona Balfe – travel to Paris in an attempt to gain the ear of Bonnie Prince Charlie and prevent the Battle of Culloden.

Gird your loins, it is time to journey deeper into the heart of Outlander. First stop on the tour is the domain of armourer Jim Elliott, who looks after the weaponry used in the many battle scenes.

Inside a 60-strong collection of broadswords lines one wall while another is filled with targes, the distinctive circular shields used by Jacobites. The guns are under lock and key in nearby containers.

Elliott hands me a Brown Bess – the British Army’s muzzle-loading smoothbore musket – and my arm almost snaps in half while trying to take aim with the unwieldy contraption, which weighs 14lb, precariously balanced against my shoulder. Sweat beads my brow simply trying to stay upright.

The Glaswegian began working as a prop master in 1990 and looked after weapons as part of his wider role. After the 1996 Dunblane massacre, new laws meant firearms used in filming required a trained armourer.

Working on Outlander and striving for 18th-century battlefield authenticity has not been without its challenges.

“This is my first big job with gunpowder because for 15 years I have stayed away from it due to its unpredictability and the Scottish weather – if it rains, it ain’t firing,” says Elliott. “That is what I have to tell the director because I’m not a magician.

“It didn’t fire back in the day. Three hundred years later we are using the same stuff and it still won’t fire. We can cheat because we have special effects and can put charges and small powders down the barrel and electronically fire them wirelessly.

“We have had bad weather, but luckily it’s not been on firing days. The worst thing for the weapons is the rain and the cold because they do rust. We come back from four days in the Highlands, open the gun boxes and there is surface rust on weapons. That means a day sitting here, cleaning swords and the muskets, just as they would have done 300 years ago.”

When we meet he is preparing his arsenal for a staging of the 1745 Battle of Prestonpans, a scene involving 600 weapons. It may be acting, but Elliott, who has previously worked on Cloud Atlas, World War Z and Under the Skin, is always switched on to potential dangers.

“Of course, it is real gunpowder,” he says. “They are test-fired in here to make sure it looks good enough on camera. We only put in 50 per cent of what it is capable of. That way it is a safer for the person using it, the camera still sees what it needs to and the viewer thinks: ‘Wow!’”

Leaving the armoury, I pass through a vast storage area where painted backdrops of scenery are stacked. High on a shelf sits a replica memorial cairn, a collection of cannons nearby. Then I see them: the standing stones.

The mystical (and fictional) stone circle of Craigh na Dun is pivotal to the plot, allowing Claire to time travel. I close my eyes and press a hand against the tallest one, but alas, when I open them again, I’m still in Cumbernauld in 2016. For now, at least …

Production designer Jon Gary Steele and set decorator Gina Cromwell have promised a whirlwind trip to Paris, starting with the quirky apothecary shop which belongs to the enigmatic Master Raymond, played by French actor Dominique Pinon.

It is an enchanting room with hieroglyphics and runes etched on the wall, shelves tightly packed with potions and eye-catching curiosities, including a jar of squids and a unicorn skull.

We head towards the cobbled courtyard which sits beneath the set serving as Jamie and Claire’s luxurious Parisian apartment – a far cry from the muddy crofts of the Highlands.

A chandelier hangs in the entrance hall with a grand staircase leading upwards to a stunning palatial interior filled with ornate furniture and plush woven rugs.

Cromwell points excitedly to a fireplace. “We moulded these beautiful firebacks,” she says. “That is something we found on our Paris trip. There was all these Rodin sculptures and we had our heads inside the fireplaces. We must have looked like odd people …”

Viewers will see the sets impeccably dressed with props including towering candelabras and gleaming silverware – right down to glasses subtly engraved with a Jacobite emblem.

“Scotland was much more utilitarian,” says Steele. “This is the opposite. It is about showing how the rich lived. I think the fans will enjoy it because it is completely different. It is the most beautiful and decadent period of art, architecture, costumes and fashion – and 18th-century Paris was the hub.”

But it is not just the backdrops that leap off the screen. What the cast are wearing is equally impressive. Costume designer Terry Dresbach greets us at her office, a busy space piled high with fabric swatches, sketches and assorted haberdashery.

On one side is her “inspiration wall”, filled with ideas for colour, context, shape and tone, while another houses a blackboard which reads “Outlander Season Deux” and a sizeable to-do list for the forthcoming Scottish scenes (“R&D Plaid!!!” being one such entry). A spaniel called Cuilean (Gaelic for puppy) snoozes in his basket beneath a white chalk heart that reads “Ron + Terry”.

Executive producer Ronald D Moore, known for his work on Star Trek and Battlestar Galactica, is married to Dresbach and it was his wife, a huge fan of Gabaldon’s writing, who introduced him to the books.

Dresbach is a colourful character, rock star-meets-Marilyn Monroe in appearance, with a pierced nose and platinum blonde hair. Dressed in a leather jacket, jeans and a pair of red Converse, everything about her is effortlessly cool.

It is a stark contrast to the elaborate costume design she has overseen on the second series of Outlander, one where the dresses are the size of small cars and with more bling than Elton John.

“Paris is spectacular and it is a fashion show,” says Dresbach. “I kept going back to Ron and saying: ‘Are you sure?’ because one of the things he and I agree on is that you have to be careful that costumes aren’t so over the top that people stop paying attention to what the actors are saying.

“As a designer you have to be able to push your costumes down a bit and let them be in a supporting role as opposed to front and centre. But he was very clear that in this piece it serves the story to have the costumes scream and shout all over the place.”

Dresbach fell in love with Gabaldon’s novels 20 years ago and has read each of them “a dozen times”. She recalls stumbling across the books while looking for something to read between film jobs.

“I started reading it with no idea of what it was,” she says. “I read it right through the night until 9am the next morning. It was such an adventure and I was so taken by Claire. It is rare to find a book with such a strong and powerful woman – they are so often the secondary characters.

“I went straight to the book store the next morning and bought the second book – and did that for three days. I read a book a day for three days. Then I ran out of books, thank God, or I might have ended up in the hospital. I had to wait six weeks for book four to come out.

“Ever since, I’ve been one of those people ordering my advance copy,” she adds, with a twinkle in her eye. “It is nice because now I get them with the editor’s notes and pencil scratchings.”

As a fan, Dresbach feared a film adaptation wouldn’t do the complexity of the characters and plot justice. But when Moore mooted the idea of a television show, Dresbach – who has worked on Buffy the Vampire Slayer and The Shield – had a notion it might just work. “I thought: ‘Maybe you won’t destroy my favourite book if you make it into a TV series,’” she recalls.

Dresbach admits it still feels “surreal” to be working on Outlander. “I can’t think about that very often because it is too odd,” she says. “I have had to try to create a little distance as a reader and a fan to being the costume designer because it gets murky. I do the costumes that were always in my head as I read the books over the years.”

Moore is famed for his nit-picking attention to detail and Dresbach is no different. “Everything is authentic and done as accurately as possible,” she says. “We had already seen quite a few forays into historical fashion on other shows. People were making very modern, contemporary versions of period costumes and we knew we didn’t want to do that. I was adamant that the 18th century is one of greatest periods of fashion ever and there was no need for me to mess with that.

“There were a lot of [period drama] shows that got hit pretty heavily [by the critics] with red circles around an extra’s shoe or a zipper on a costume. We have been scrupulous about making sure everything is as authentic as possible.”

That sentiment goes likewise for the Scottish costumes. “There is a controversy around tartans which has gone on for years about the authenticity of the really brilliant colours,” says Dresbach. “We knew we didn’t want people prancing around in the heather in brilliant red and orange tartan.

“Learning what I have about Scotland, it didn’t make sense to me that in a poor croft, a dark and windowless building with the fire going in the centre, a couple of pigs in the corner and three generations of people living there, that you would be sitting there trying to get the perfect shade of scarlet. It made much more sense that garments would be simpler and go about the business of living.”

The second series of Outlander has meant going back to the drawing board with more than 10,000 items made by the costume department. That included producing 900 French extras’ costumes from scratch because, says Dresbach, there was “nothing from Scotland that could go to Paris”.

It has been a painstaking process with intricate embroidery a key component of the French fashions that have kept Dresbach and her team working round the clock. While the designs stick steadfastly to 18th-century tradition, modern technology has played a vital role.

The embellishment on a men’s frock coat and matching waistcoat could take up to two months to sew by hand, but using an industrial embroidery machine is typically completed within two days. “We had to create 1,000 in less than a year – it wouldn’t have been possible otherwise,” she says.

Everything on Outlander is large scale and that includes the number of buttons used in costumes. “We tramp around the world trying to buy buttons,” says Dresbach. “We bought 50,000 and that still wasn’t enough, so we started to look at how to make our own.”

Stepping inside a storeroom, Dresbach apologises for it being “empty and echoing” as most items have already been shipped to Prague which has doubled as Paris in some of the street scenes (although the lion’s share of filming has remained in Scotland).

In a corner, the rails are starting to fill up with the “dribbles and drabbles” of Scottish costumes. There are boxes labelled “poor women’s shoes” and “upper-class women’s shoes” (5,000 pairs were acquired for season two) alongside several rows of grubby-looking British army Redcoat uniforms.

“We made all of our Redcoats,” says Dresbach. “We didn’t have to make all of them, but there is this showrunner guy” – she gives a mock eye roll – “who ranted to me for years about how nothing he ever sees on camera is the right shade of red for Redcoats. He said when we did Outlander it had to be right.

“The one costume we could have rented lots of was Redcoats, but we couldn’t because Ron didn’t like the colour of red. Instead, we had to dye fabric to his colour specifications and make our own Redcoats. He wanted a deeper, richer red rather than a bright cherry/candy apple red.” Dresbach bites back a grin. “I will never let him live that down …”

Adding to the overall look, each of the uniforms has been sent to the ageing and dyeing department where garments are “attacked and destroyed” with an industrial spray gun.

“All of the seams will look like it has been worn and not laundered for a very long time,” explains Dresbach. “That happens to just about every single costume we have. Sometimes we hit them with blow torches and burn down the fabric.”

The Battle of Prestonpans is still to be shot when we meet and Dresbach wants the Redcoat jackets to be surrender – or “turncoat” – ready. “The lining fabric has to look old,” she says. “We are going back to our Redcoats and ageing them on the inside.”

Leaving Dresbach to her button collection and blow torch, my time on Outlander has come to an end. I lay a hopeful hand on the standing stones one last time as I leave, but it’s back to Glasgow for me.

Outlander series two will be available on Amazon Prime Video from April 10 with new episodes airing weekly

Read more: Outlander star Sam Heughan on Scottish independence, super fans and his life changing role as Jamie Fraser

Read more: Caitriona Balfe on the secret ingredients that made Outlander a global hit