When Raising Sand - Alison Krauss's 2.5 million-selling album with Robert Plant - won six Grammy Awards, her tally of the gongs reached 26, more than that of Aretha Franklin, Madonna, or any other female music artist. A certain degree of diva-dom sometimes accompanies such stratospheric success, so, waiting for her backstage at The Sage, Gateshead, England, I'm half expecting Krauss to swan in with an entourage.
"Thanks for coming!" she smiles, arriving alone. Without make-up, and dressed in a tomyboy-ish, decidedly offstage outfit of purple sweatshirt, jogging pants and trainers, Krauss, 40, still seems more girl-next-door than reigning queen of Bluegrass. Self-effacing and softly spoken, she describes herself as "a bit of a hermit; someone a little out of step with the modern world". When we decamp to her dressing room I notice it's bare, save for a pack of McVitie's Hobnobs. "Man, your English cookies are so great!" she says. "Robert [Plant] made fun of me for eating so many."
Outside the US, Krauss is still best known for duetting with the aforementioned Led Zeppelin legend, but back home this singer and fiddler has sold more than 12 million albums with her own band, Union Station. Still, by her own estimation Union Station has yet to go mainstream. "Bluegrass music just isn't that commercial," she says. "We're mainly promoted through word of mouth."
Born in Decatur, Illinois, but currently residing in Nashville, Krauss signed to the esteemed roots music imprint Rounder Records when she was 14. Years later, when T-Bone Burnett came to produce the soundtrack for the celebrated Bluegrass music-fuelled film O Brother, Where Art Thou?, Krauss was a trusted contributor and consultant.
Another O Brother session player, the singer and guitarist Dan Tyminski, co-fronts Union Station with Krauss, and at gigs she jokingly introduces him as "the voice of George Clooney". Between them, Krauss and Tyminski have probably done more to propagate Bluegrass than anyone since the inventor of the banjo. But after all these years, what is it that brings Krauss back to the well?
"I just love the message of Bluegrass," she says, pulling at tousled blonde locks various hair-clips are failing to tame. "It's a fantasy about simple life and basic values and there's not too much psychology or over-thinking things. It's 'one woman and only this woman', you know? It's 'I believe this and only this'. It's 'I killed this person and I should have', or 'I killed that person and I shouldn't have'. It's very black and white and I love the picture it paints about home and family."
Krauss and Union Station are in the UK to play shows promoting a deluxe edition of her 14th album Paper Airplane. Exquisitely rendered but unremittingly melancholic, the album had a tortuous gestation, with Krauss's suffering from insomnia and acute migraine headaches stalling progress, but which doubtless lent extra weight to songs such as Lie Awake.
The most revealing song choice on the album is perhaps Krauss's cover of Richard Thompson's Dimming of the Day, the tender 1973 ballad that documents Thompson's divorce from his wife Linda. "It was almost too painful to sing," Krauss concedes quietly, but then her empathy is easy to understand. It's well-known that she brought up her son Sam (now 12) as a single mum having divorced from his Bluegrass musician father Patrick Bergeson in 2001. So why sing Dimming of the Day if it opens up old wounds?
"I have to sing songs that move me," says Krauss a little guardedly. "When I'm singing those songs and I relate to them, it's not torturous. It's a healing thing for me and that never gets old. I think that people respond to honesty in music, so I only choose songs that are the truth for me. You have to go with what you feel you have to say.
"Even when Dan [Tyminski] sings Dust Bowl Children and it talks about hard times for the farmers ... well, for me that's a metaphor. A relationship can become a dust bowl if you don't tend it well, you know?"
As our interview winds down, Krauss and I broach other topics. She's "not a big internet person" but likes history and has been reading up on the Easter Island statues. People laugh at the ancient TV set she rarely watches and only recently retrieved from her basement. Her migraines continue to come and go. The fiddle she's played for the past 30 years came to her via the widow of a Louisville, Kentucky, collector named Alan Harris.
There's a quiet warmth and vitality about Krauss, but one detects a certain sadness, too. Is she happy with her lot in life?
"My faith and my respect for God are at the core of everything I do," she says. "That gives me a hope that I don't think I would have otherwise. I don't look for bliss - just contentment. I don't know if bliss is possible and I've always thought that my best times will be later in life."
The deluxe edition of Paper Airplane is out now