SPENDING time on the set of Still Game is like stepping through the looking glass in Alice In Wonderland.

The BBC Scotland comedy returns to our screens on Thursday. Penned by Ford Kiernan and Greg Hemphill, the eighth series was shot in and around Glasgow last summer.

A grey and cloudy August morning finds the cast and crew filming in Ruchill Park. Within minutes, the leafy space is abuzz with activity as monitors are wheeled into place, cameras set up and props organised.

Death is a theme that looms large in the latest series of Still Game. Bruce Morton has joined the cast as the ominous sounding "undertaker" and ever since word leaked out that a long-standing character will depart Craiglang in a coffin, there has been feverish speculation abound.

Viewers are being told to brace themselves for a darker undercurrent to upcoming episodes, with the bookies taking bets on which fan favourite might meet their maker.

Funeral director Iain Duncan Sheathing – played by stand-up comic Bruce (who famously introduced the show's co-creators Ford and Greg in the 1990s) – has been dubbed "the living embodiment of the Grim Reaper".

There will be a touch of Hollywood glamour arriving in Craiglang, too, with US-based talk show host Craig Ferguson playing an old friend of Isa's who returns to Scotland after living in Los Angeles.

Filming in the park alongside Ford and Greg is Gavin Mitchell, who plays Boabby, the long-suffering barman from Craiglang's local pub, The Clansman.

Gavin is on sparkling form as he pops over for a chat during a break in filming, the actor clearly relishing being back in character.

The previous take was halted when the trio descended into unscripted laughter – corpsing as they call it in the business – and Gavin is still fighting bubbling giggles as he walks off set.

Ford is apparently getting the blame for that one. "He's brilliant and can just move his eyes or do a quick head turn and make me laugh," grins Gavin. "We know how to tweak each other's chuckle muscles."

Up close his hair – or rather Boabby's mane – is a sight to behold. Gavin gives the long, dark wig a dramatic flick. "It's like Aslan," he says, referencing the lion in CS Lewis's The Chronicles Of Narnia.

"If only it was my own. It is phenomenal. Boabby's hair has grown in colour, length and volume. I'm like one of Charlie's Angels now."

When does he cease being Gavin and morph into Boabby: it is the wig, chunky gold jewellery or retina-searing shirt collection?

"It is kind of odd," he muses. "The final touch is actually when I'm in The Clansman and put on the dish towel. If he doesn't have his dish towel, I feel a wee bit naked.

"Boabby always has his towel. That and walking into The Clansman which, for Boabby, is almost like his Tardis.

"Last series the first scene was in Navid's which felt very strange. It was fish out of water. I was like: 'Hold on, I don't belong in here and I don't have a dish towel. I don't know how to act ...'"

Death is in the air. When did the cast get a whisper of that? "We were as surprised as everyone else because we don't find out until we get the scripts," he says. "Then we were like: 'Oh, my God!' The stakes are high throughout this series. Mortality plays a big part.

"It has always been a mark of Still Game and the brilliant writing that, in among all the laughs, there are really serious issues and we address that. It can turn on a pin from laughter to tears."

We're interrupted as Gavin is called back onto set. He gives a theatrical wave, adopting a comical, hammy accent: "Excuse me, I must dream weave …"

He stalks off leaving everyone doubled up with laughter. I'm curious to learn more about the food being used in the scene which includes something called a "beefy bake" – a savoury, meat-filled pastry not a million miles from the trademark staple of a well-known bakery.

According to the art department, they typically bring six duplicates of each prop. With beefy bakes that figure is doubled for very good reason. "Normally the boys like to eat them," explains one crew member. "But today they don't seem to be in the mood ..."

A few minutes later, Gavin returns and takes up the thread again. "There are loads of surprises this series and quite a lot of good stunts," he says. What kind of stunts?

"Well, you saw an amazing stunt there with a beefy bake," he deadpans. "What more can I say? Not everyone can handle a beefy bake like that. That took weeks of training. We all had to go to a beefy bake course …"

Still Game returns to BBC One, Thursday, 9.30pm