For those raised in Britain in the 1970s and '80s, black-and-white comedy legends Laurel and Hardy were part of your teatime TV diet. It's how Jon Baird, the Aberdeen-born director of the affectionate new biopic Stan & Ollie remembers them. Same goes for his cast. 'It was just part of the landscape,' says Steve Coogan, who plays the British-born Laurel opposite John C. Reilly's Oliver Hardy. 'It was just there, part of growing up,' nods Scottish actress Shirley Henderson, cast as Hardy's wife Lucille.

If Laurel & Hardy are no longer a showbiz staple, Stan & Ollie looks set to change that. 'I hope when the film comes out, it gives them a new lease of life,' says Baird, who effortlessly shifts from his hard-hitting 2013 Irvine Welsh adaptation Filth to this gentle look at the off-screen bond between one of Hollywood's most successful double acts. While Baird estimates that kids today – including his 8 year-old daughter – still find these bowler-hatted bumblers funny, that's not quite this movie.

'This particular film, it's not a comedy,' he says. 'It's more of a love story, an emotional tale.' Scripted by Philomena's Oscar-nominated screenwriter Jeff Pope, it follows Laurel and Hardy as they tour British theatres in 1953 hoping to reignite their fading Hollywood careers. 'It was more interesting to focus on a period of their career when they had challenges,' says Baird, 'whether it was financial, health personal relationship worries. They had a lot going on at that period in their life. They had a lot of struggles to get over.'

Amid all this is two career-best performances from Coogan and Reilly (the latter received a Golden Globe nomination for his turn). As Baird recalls, 'Reilly said something to me which was really interesting when I met him about the project: "The prospect of playing Oliver Hardy is terrifying but it's not as terrifying as the thought of letting someone else play him!" I thought, I love that! He's not going to let this go. If he takes this on, he's going to give this everything. And he did…the pair of them did.'

With Coogan and Reilly brilliantly emulating their characters' tics and tricks, they also had to find the men behind the on-screen magic. 'It does involve both mimicry and something more profound,' says Coogan. 'But it's a marriage of those things.' When it came to learning the steps for the dance performed in the duo's high-point, 1937's Way Out West – glimpsed in the film's bravura prologue – they even learnt 'their mistakes in that routine', the actor adds.

The comic genius behind Alan Partridge, Saxondale and The Trip, Coogan innately understands what made this pair so successful. 'Within all of the precision of the comic beats, underpinning it all was quite a simple humanity,' he says. And it's this that the film hones in on, examining everything from friendship to facing your own mortality. While Hardy and Laurel were both in relationships (Nina Ariande plays Laurel's fourth and final wife Ida), theirs was akin to a long-term marriage.

'With that comes respect for each other and also great annoyance, because you're spending so much time together,' says Shirley Henderson, who gained valuable insight into Hardy by listening to recordings of Lucille. 'She said he hated being fat. She would be sitting at her dressing table, brushing her hair, and he'd come in behind him and say, "How can you possibly love a man like me?"' It just goes to show that even when you spend a career making people laugh, happiness can sometimes be out of reach.

Stan & Ollie is in cinemas from Fri 11 Jan.