Alison Krauss: O Brother! The country girl who met the Led Zep legend

Her album of duets with the singer Robert Plant, and work with the Coen brothers, has brought the bluegrass star global acclaim. But she tells James McNair that she's still a simple girl

Backstage at The Sage, Gateshead, the phrase "hob-nobbing with the stars" has taken on a different meaning. The McVitie's oatmeal biscuit of the same name is much loved by Alison Krauss, and a pack of the treats is brightening the singer's day post-sound-check.

Such simple pleasures seem curiously typical of this 26-time Grammy award winner and reigning bluegrass queen, a woman who is, by all accounts, very low-maintenance. Warm but wary, sans make-up, and dressed in a tomboy-ish, decidedly off-stage outfit of purple sweatshirt, jogging pants and trainers, Krauss deflects compliments and describes herself as "a bit of a hermit; someone a little out of step with the modern world."

Presumably her band-mates fussed over her when she turned 40 on tour back in July, I enquire.

"Oh no!" she says, pulling a goofy "appalled at the idea" face. "I'm not a big party person and I wouldn't want them walking onstage with a cake..."

My interviewee's distinct lack of diva syndrome reportedly impressed Robert Plant when the pair duetted on 2008's 2.5 million-selling album Raising Sand, but other factors – Krauss's impeccable bluegrass pedigree, her impish, apple-shaped cheeks – were doubtless a draw, too.

Signed to esteemed roots-music imprint Rounder Records when she was 14, this gifted Decatur, Illinois-born fiddler and singer had a residency at the Grand Ole Opry by the time she was 21. When T-Bone Burnett came to produce the soundtrack for celebrated bluegrass-fuelled comedy film O Brother, Where Art Thou?, Krauss was a trusted contributor and consultant.

Another O Brother session player, the singer and guitarist Dan Tyminski, continues to co-front Krauss's band Union Station today, and, at gigs, Krauss 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", 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." But for her it's just a fantasy?

"Well, when I say fantasy, I don't mean that it isn't truthful," the singer qualifies. "When I listen to Charlie Louvin's music I hear about the hard times in life and the beautiful times. It rings true and I can get lost in it."

Talented, phenomenally successful – and let's face it wealthy – Krauss may be, but such blessings are, of course, ultimately unable to prevent life's tougher challenges. It's well known that the singer brought up her son Sam (now 12) as a single mum, having divorced from his bluegrass musician father Patrick Bergeson in 2001, but Krauss and those around her guard her privacy closely, and if she has dated anyone since Bergeson, names are not something search engines proffer at the click of a mouse.

One of the key tracks on Paper Airplane, the fine but unrelentingly melancholic 2011 album that Krauss's UK tour is promoting, is her take on Richard Thompson's masterful 1973 ballad, "Dimming of the Day". First sung by Thompson's wife Linda while the couple were going through their own divorce, it's obviously a song that has resonance for Krauss. So much resonance, in fact, that she declined to sing it on Jools Holland's Later... earlier this year for fear she might break down.

"Goodbye is All We Have"; "Ghost in This House"; "Too Late To Cry" – Krauss's back catalogue is riddled with heartache, while part of Paper Airplane's title track runs: "Every silver lining always seems to have a cloud/ That comes my way." That old joke that, if you play a country record backwards, the crop doesn't fail, your dog doesn't die, and your partner doesn't leave you, reminds us of the genre's pact with adversity. Still, if you're hurting, doesn't singing country aggravate matters?

When I'm singing those songs and I relate to them it's not tortuous," says Krauss a little guardedly. "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. Whenever I've chosen a song because it's clever, it's always turned out to be a mistake." So there isn't a part of her that would like to sing Sly and the Family Stone's "Dance To the Music" every night?

"Sure, I love that song! That and [Stone's] "Thank You (Falettinme Be Mice Elf Agin)" are so great. I sing along and I can participate in those feelings, but that's not my musical identity right now. Maybe that will change – I don't know. If it does, Sly and the Family Stone is what I'll end up singing."

Krauss says that she learned a great deal working with Robert Plant, not least the value of "capturing the moment". It's no secret that the pair started work on a follow-up to Raising Sand, but, by mutual agreement, they later abandoned the new recordings.

"I think it was just too soon," she says when asked why the stars didn't align second time around. "We had an amazing band in there, but the music sounded like an extension of the first album and we were looking for something that had a fresh identity of its own. I guess it was a bit optimistic to expect lightning to strike twice, but I wouldn't be surprised if we try again at some point. "

As our interview winds down, we broach other topics. Krauss tells me abut the cherished fiddle that came to her via a Louisville, Kentucky, collector some 30 years ago, about the migraine headaches that plagued her during the making of Paper Airplane, and about the ongoing insomnia that doubtless led her brother Viktor Krauss and songwriter Angel Snow to pen new album standout "Lie Awake" for her.

She says that her respect for God is at the core of everything she does, and that her faith gives her a hope she doesn't think she would have otherwise.

"I don't look for bliss, just contentment," she adds. "I don't know if bliss is possible and I've always thought that my best times will be later in life."

Later that night it's a beautifully made-up and much more glamorously attired Krauss who takes the stage in Gateshead. Her own virtuosity is on a par with that of Dobro-master Jerry Douglas, but she still comes across as the most unassuming of bandleaders.

"Why do we play all these sad, sad songs?" she jokes at one point. "Well, I guess we're just sad, sad, people!" It's probably an established line of stage banter, but it feels as though she's poking fun at my line of questioning. The subtext? Simply that melancholy can be enjoyable.

The deluxe edition of 'Paper Airplane' is out now on Decca. The single "My Love Follows You Where You Go" is out on Monday. Alison Krauss and Union Station play the Royal Festival Hall, London SE1 (020 7960 4200) 12 to 15 November