An hour into Emerald Fennell’s Wuthering Heights, Margot Robbie is in a gauzy wedding dress, gliding forlornly across the moors towards the man her character feels she has to marry. A lone female English voice appears to accompany her, high and pure against the buzzing drone of a harmonium, singing about a woman roaming alone, and a man who, for “seven years, left the land”, before his eventual return.

Long before Emerald Fennell found Olivia Chaney’s version of 19th-century ballad the Dark Eyed Sailor online, Chaney was preparing to sing it for a 2013 live session on Mark Radcliffe’s BBC Radio 2 folk show, in the midst of her own Brontë-esque love triangle. “I was at the beginning of my relationship with the man who is now my husband and the father of my two children – he nearly married someone else, and I nearly had kids with someone else.”

She recounts this from her Yorkshire living room, minutes after getting home from the nursery run. “So to see this song first pop up to support Cathy’s emotions around her being with the wrong man … it was very spooky.”

Fennell told Chaney she was choosing between three of her songs for the film. She settled on this one “because she connected with it”, says Chaney. “There’s something about the way she uses my voice, not surrounded by [an] orchestra at all, that shows how raw and emotional I felt.”

The song’s rescue from the vaults came at a serendipitous time for Chaney, a wide-ranging artist recently returning to folk. Her previous three albums, mainly of originals, include 2024’s Circus of Desire; its title track was remixed by Vessel, and Chaney’s dancing in the video recalled the two years she spent singing live with Zero 7. On 27 February, she plays her first gig with her new British folk-rock band, News From Nowhere, which has quite the lineup: Tom Skinner, the drummer from the Smile and Sons of Kemet (“one of my favourite musicians on earth”), Owen Spafford on violin and electronics, singer-songwriter Clara Mann, and composer/producer Leo Abrahams, with whom Chaney recorded her debut EP the same year as that fateful Mark Radcliffe session.

Chaney discovered folk music as a path for herself in her 20s. She knew some folk-rock and singer-songwriters from her parents’ record collection, but she sang Hildegard of Bingen’s music with the Oxford Girls’ Choir, and won a scholarship to Chetham’s School of Music at 14 to study voice and piano, going on to study jazz at the Royal Academy of Music in London in 2000.

Seven years later, after being stood up on a date – “a bit blue, really in my own world, and not knowing where to go with my singing” – she went to an afterparty with friends at London’s Southbank Centre. “And I saw this really shy busker playing this heavenly music. I ran over, begging, ‘What are you playing? Who are you like? Do you want to work together?’” The busker, Matthew Ord, now a lecturer in folk music at Newcastle university, was playing Planxty Irwin, a tune by the 17th-century Irish composer and blind harpist Turlough O’Carolan.

Ord taught Chaney many traditional songs, including Dark Eyed Sailor: “I really responded to the words and the emotions in it,” she says. Then, one day, he turned up at her house with a harmonium and asked if she wanted to play it. “And that was that.”

Chaney became one of Britain’s most exciting new folk performers, earning the respect of veteran folk artists. She supported Shirley Collins on her 2017 tour, sang with Richard Thompson at his 70th birthday concert at the Royal Albert Hall and performed at last year’s all-star tribute gig to Martin Carthy in Hackney. She also fronted folk-rock supergroup Offa Rex with the Decemberists; their brilliant 2017 album, Queen of Hearts, was nominated for a Grammy.

This summer, she’s also releasing an album of songs by composer Henry Purcell and performing them with a chamber ensemble at the London venue Kings Place, where she’s an artist in residence this year. “Purcell wrote for kings and queens, but he was also down the pub listening to the ballads and the broadsides,” says Chaney. “His ability to write a catchy tune, almost like a pop hook, made his songs go straight back into the street culture of the day. I’m so interested in those connections.”

That cross-cultural mindset is typical of Chaney’s outlook. The only other voice heard singing in Wuthering Heights is that of Charli xcx, who produced a companion album to the record. “I think her music’s great and very harmonious with my song – it all ties in really well together,” says Chaney. “Even though there are some bangers, harmonically they are in a similar world to Dark Eyed Sailor. There’s even synths and sounds that are in a similar sonic tonal world to my harmonium.”

For years, Chaney’s version of Dark Eyed Sailor only existed in live YouTube clips, but she finally released a recorded version last Friday, produced by Oli Deakin (mastermind of CMAT’s albums If My Wife New I’d Be Dead and Euro-Country). She’d recorded “many” versions of it before – three were even mastered for albums, but “never quite fit”. She finally heard it fit at the Wuthering Heights premiere in Leicester Square on 5 February.

What was the evening like? “Drinking champagne behind Richard E Grant?” She laughs. “Insane. I gripped my husband’s hand so tight when the song came in – hearing my voice all alone – that it reminded me of giving birth, gripping my doula’s hand so hard I nearly broke her knuckles!”

The song appears again when Heathcliff returns to Cathy, now rich and grown up, and in the film’s final, longing minutes. It’s always been Chaney’s husband’s favourite recording, she adds. “It’s a song I love very much. It comes back and haunts you.”

• Olivia Chaney’s residency at Kings Place starts on 27 February.