AULD Lang Syne, the song at the centre of Mairi Campbell’s new show, is, “an old chestnut; a song that everybody knows but nobody knows”.

A weel-kent face on Scotland’s folk scene, Campbell is back at the Edinburgh Fringe with her second one-woman show, exploring probably the world’s most weel-kent song.

“It’s sung in China, sung in Japan, and it’s a football chant in the Netherlands,” the musician says.

READ MORE: Father of Scotland’s folk revival celebrated in Fringe show

But she adds, it was Guy Lombardo, the Italian-Canadian bandleader, who really helped the song take over the world.

Campbell quotes Life magazine, which said “if Guy Lombardo failed to play Auld Lang Syne, the American public wouldn’t believe the New Year had arrived”.

“People don’t always know the rituals, the pronunciation or the meaning of the song,” Campbell adds.

Her show, she says, will help explain all of that.

Auld Lang Syne, is the follow up to 2016’s well received Pulse, and tells the story of the song, and the story of Campbell’s own life and career.

The song and Campbell’s career are inextricably intertwined.

A version of the song was on The Minnowing, the first album released by her band, The Cast, back in 1994.

While the words are familiar, the tune is not, with Campbell and musical partner and husband, David Francis, using the music Rabbie Burns had originally intended the song be sung along to.

Back in 2006, that haunting rendition was – in a complete surprise to the two – picked up by the producers of the Sex and City movie and plays, in full, over an emotionally charged New Year scene.

That film, which became one of the highest-grossing of the year, helped the song become an internet sensation, and catapulted Campbell towards an unexpected level of fame. Videos with the song have been watched more than 10 million times.

There’s still a little confusion about how the film’s backers picked up the song, though there was a suggestion it was heard by someone close to the movie’s producers when Campbell and Francis performed it at the Kennedy Centre Awards in 1999 when they played the song for Sean Connery.

Auld Lang Syne, which opened in Edinburgh’s Storytelling Centre on Friday and runs for the next three weeks, centres on the song, Campbell’s marriage and her friendships.

“It’s sort of trying to bring the song, communicate what the song is about, at some level and explore its themes of friendship of leaving, breaking up, making up, distance in physical and emotional realms. That’s what I’m doing really,” the musician tells The National.

READ MORE: Fringe spotlight: Scotland, Quebec and questions about the future

Campbell says the show is also very personal, exploring her marriage with Francis, and an old friendship with Catriona, rekindled after they lost contact for a “long, long time”.

The two have been consulted on their parts in the show.

“They have to be fine for it. They’ve seen the script. They have to be okay with what’s going to happen.

“That whole thing, it feels like an exposure in this way, It’s good.”

Catriona, she says, is excited about the show. It’s unclear if Francis is as excited.

She laughs. “It’s serving the song. It’s in service to the song. That’s what I’ve been trying to tell Dave, anyway. Get over yourself man, this is in service to the song.”

Campbell, who spent decade touring Scotland is still finding the Fringe a novel experience. Or at least the theatre side to the Fringe.

“I’ve been a gigging musician all my life and we don’t tend to get that involved, we certainly don’t do full runs at the Fringe, we’d do a night at the Acoustic Music Centre. Three weeks, what? But it is the thing you do. It’s only since I got in tow with [show director and co-creator] Kath Burlinson and that more theatre culture crowd that I’ve saw seen a whole different way of doing it and that we’re sitting on a fantastic opportunity in Edinburgh. It’s all right here.”

The show was one of the 23 shows to be picked up for this year’s Made In Scotland showcase, which helps Scottish artists to bring work to the world’s largest arts festival.

She adds: “It’s a really fun odyssey of childhood, and adulthood and relationships and at the end of it I just try and bring the whole room together and somehow articulate that we’ve ‘wander’d mony a weary fit’.”

Mairi Campbell: Auld Lang Syne, Scottish Storytelling Centre, until 27 August 16.30