The Swedish sibling songstresses cite some unusual inspiration behind their success...
First Aid Kit's Klara and Johanna Söderberg have been making music together as a duo since 2007, and have been sisters for somewhat longer.
Mixing a naturalistic, folk roots sound with a country twang, the pair's music creates a world somewhere between the woodlands of their Stockholm suburb home and the wide open spaces of the American West.
Following on from local success with their home-recorded demo Tangerine, the pair released their debut EP Drunken Trees in 2008 and their debut album The Big Black & The Blue in 2010. They went on to spend much of the following two years touring the world, picking up celebrity fans including Jack White and Bright Eyes along the way.
Now new album The Lion's Roar - recorded in Omaha with Bright Eyes' Mike Mogis - sympathetically fills out their sound without losing the immediacy of the pair's close-harmony vocals, and has proved their most successful to date, entering the Swedish charts at No.1 and receiving glowing reviews worldwide.
New single Emmylou's chorus, "I'll be your Emmylou and I'll be your June / if you'll be my Gram and my Johnny too" wears its country colours on its sleeve, and uses the legendary musical and personal partnerships of June Carter and Johnny Cash and Emmylou Harris and Gram Parsons as metaphors for an idealised relationship
Talking about why they picked the two musical pairings as lyrical inspiration, the sisters also revealed that the song has involved them in a slight case of accidental plagiarism:
Klara - "Both couples just harmonised so well with each other it was something really special. Johnny and June were obviously married as well and although Gram and Emmylou were never married I've read things about how Emmylou was secretly in love with Gram and was going to tell him but then he died."
Johanna - "So it's just really tragic, it's a sad song really."
K- "There's actually a Gillian Welch song (I Dream A Highway) which I hadn't heard when I wrote it which goes‚ 'Now you be Emmylou and I'll be Gram'. We later read an interview with Gillian in a Swedish magazine where they played a bunch of songs to her, including Emmylou, and she went "Hey, maybe they took this from my song' and were 'Noooooo!'. So now a bunch of people think we took it from her!"
The use of nature and characters as metaphor have been recurring themes in the Söderbergs' songwriting from the start, although as the pair experience more of the world at first hand their lyrics have become more personal and less abstract.
K - "That was something that we particularly wanted to do with this record. We wanted to use less nature metaphors, although there are still plenty of those because we love them, but now we're older we have a bit more to draw from when writing. There's still plenty of stories on this record though.
J - "I think with us it's never going to be strictly autobiographical though, it's always going to be a mix - and sometimes you're able to tell and some times you're not."
K - "All our songs are based on pretty universal emotions. There are songs like Blue or This Old Routine where we're talking about people who are are middle aged. This Old Routine is about this man who is looking at his family and realising that they're not communicating, just living their lives and the love is gone - there's just nothing there.
"Blue is about this woman who looking back at her life and regretting the things she didn't do. We sort of write about our fears of the future and regrets we may have kind of as a warning to ourselves - 'Don't become these people', rather than just 'Oh, I'm 19 and I'm scared about the future.'"
The pair obviously enjoyed the process of making the new album, but will the shift to working with others in new environments affect their songwriting in future?
K - "We always want our songs to be able to be played as just as guitar and vocals, and I think all good songs do with our needing to add anything - so we always work from that first.
J - "We do now think of other sounds we could use, but we don't rehearse or write with a band, it's always just the two of us. I think it will be different for us on the next record though, especially if we get to work with Mike again it will be a totally different thing and we'll get to experiment a lot more.
"The experience this time has opened up our minds to a lot of potential, so the next record will be interesting.
"We're very happy with this record, but we could probably make a better record than this one now. We feel like we're getting better everyday."
Despite starting their musical career while still schoolgirls, First Aid Kit's music has always displayed a lyrical maturity - something they partly credit to a rather unusual inspiration:
K - "I'm allergic to gluten."
J - "And you have diabetes!"
K - "Yep, I have diabetes too - I'm a sick kid! I discovered I was diabetic at nine and allergic to gluten about ten, they're kind of connected."
J - "I think it's affected you as a person, it's made you very responsible."
K - "Well you have to be. When you're 9 years old it's a big thing when suddenly everything you do you have to think about first - you can't just eat that candy you want anymore, you have to take your insulin shot. You have to learn to take care of yourself otherwise you feel like shit."
J - "I think that made you a lot more mature, and that's why you write such good lyrics."
K - "Yes! It's all because of diabetes!"
J - "And that's why we're called... First Aid Kit!"