IT'S late October and the air beneath Auld Reekie is cold. But is there something about the chill in the atmosphere of the ancient vaults under the cobbled streets that has nothing to do with the autumn weather? That’s what actor and writer Greg Hemphill and I are aiming to find out.

At one point we stand shivering by candlelight as our caped tour guide Lydia tells tales of bodysnatchers, ghosts and ghouls. The weak light starts to flicker, the thick stone walls and low ceiling seem to close in and all of a sudden a loud scream makes me – a grounded type not usually moved by thoughts of the supernatural – jump. We collapse with laughter: this is exactly what we’re here for, the sort of gleefully manufactured scary moment Halloween is all about. And it’s just the sort of feeling Hemphill hopes to give audiences in his new Halloween black comedy for BBC Scotland.

Halloween is clearly a big thing in the Hemphill household, as highlighted by the amount of time and effort he and his family put into the spookiest time of the year.

“We have eight boxes of decorations for Halloween and one box for Christmas,” he tells me with a mischievous smile once my blood pressure has returned to normal. “We’ve been decorating the house for about 15 years and we’re known as a bit of a destination for Halloween fans to come and do a bit of guising. It’s funny because our neighbours have had to up their game too. I absolutely love Halloween.”

Such gleeful appreciation is perhaps linked to the fact that as a Scots Canadian – he emigrated from Scotland to Montreal with his family as a child in the late 1970s, returning as a teenager – Hemphill comes from the country that pretty much invented Halloween, but grew up in the North American culture that popularised it around the world. He admits his dual nationality can cause a bit of friction with his wife, actor Julie Wilson Nimmo, when it comes to guising rituals.

“We always argue about whether they have to do a turn,” laughs the 46-year-old father-of-two and Still Game star. “When I was a kid in Canada you just chapped the door and said: ‘Trick or treat?’ But Jules always says that because we’re in Scotland all the kids who come to the door have to do a song or a joke. So I have to sit and listen to all these turns. I always want to shout: ‘Just shout "trick or treat" and we’ll give you a sweetie,’ but Jules won’t have it.”

For centuries Scotland has revered All Hallow’s Eve, introducing the traditions that the Americans eventually sold back to us (replacing turnip lanterns with pumpkins). But what is it about the Scottish psyche that draws Scots to the spookier side of life? According to Hemphill, it’s all about darkness.

“I think symbolically the death of summer, the end of the harvest, the coming of the winter, plays into it,” he explains. “And the coming of the darkness – we really feel that in Scotland. As I get older I really notice it. Once the clocks go back there are months of fairly harrowing indoor life ahead. These things play into the myths around Halloween. And, of course, we just really like being scared.”

Hemphill reckons Scotland’s creative community is missing a trick, and could do more to exploit Halloween.

“In 10 or 20 years I hope the film industry will burgeon in Scotland around horror films,” he says. “We have so many legends and myths – think of the kelpies, Tam o’ Shanter. There’s a culture there already.

“The best horror movies are unnerving rather than ‘jump’ scary. I’m thinking of things like The Blair Witch Project, Don’t Look Now, Rosemary’s Baby and The Wicker Man, which is one of my favourites. They leave you feeling uneasy. We Scots are the obvious people to make films like this.”

Hemphill and his co-writer Donald McLeary got the opportunity to try their hand in the genre when BBC Scotland commissioned them to write what was originally meant to be a Hogmanay story, West Skerra Light.

It stars a host of Scottish talent including Wilson Nimmo, John Gordon Sinclair, Lorraine McIntosh and John Michie, best known as DI Robbie Ross in Taggart, and follows a group of city folk as they arrive on the fictional Isle of Skerra to view a lighthouse which is up for sale. But a malevolent force is at work and all those who step foot in the lighthouse are cursed, precipitating a host of supernatural encounters – and a good few laughs.

“We wrote the script but the commissioners didn’t think it had the right tone for Hogmanay, which is a time of reflection," says Hemphill. "When they suggested it was more suited to Halloween we were delighted – Halloween is like our Hogmanay.

“It was so good to get the chance to do something like this, which is a first for BBC Scotland. The best horror takes you on a journey. There is always a device, a reveal, but if you know what the device is too early, the film loses its momentum. We tried to create as much suspense and tension as we could, have the audience wondering what was going on, and then once they realise what it’s all about, break for the border and make it fun and exciting for the last bit. Once the cat’s out the bag, you want to make it fun.”

Suspense and fun are exactly the words that spring to mind when watching West Skerra Light, a pitch-perfect Halloween treat for all the family filmed in Stranraer. But how do you get the tone right on a project like this?

“Horror is really tough actually, as is comedy,” says Hemphill. “People don’t scare or laugh easily – you have to really touch a nerve. But we were helped by the location. Scotland is such great terrain for creating spooky stories as there are massive bits of it that still feel remote, where there is no mobile phone signal. That really helps horror.

“When our communications are removed we feel like we are stepping back in time, even by 10 or 20 years. We wanted to make something enjoyable for people who didn’t necessarily like The Exorcist or Evil Dead, something more like an intense episode of Doctor Who, where you are unnerved and a bit scared, but where you’re sitting down with your families and watching a good yarn.”

Back in the vaults, our time with Lydia and the ghosts of old Edinburgh is drawing to a close. A party of foreign tourists is queuing up outside, relishing the opportunity to be scared out of its collective wits having paid good money for the privilege. Hemphill and I share a knowing look – Scotland really is awfully good at this Halloween thing.

Maybe I’ll head round to his house for guising – but certainly not trick or treating – this Monday night.

With thanks to Mercat Tours in Edinburgh. For more information visit mercattours.com. West Skerra Light is on BBC One at 9pm on Monday.