You started playing piano at the age of seven – was music always what you wanted to do professionally?
No, I always wanted to be a either writer or a hairdresser when I was a kid (laughs). Music was just something that I always loved doing, and it came very naturally to me. I guess I didn't really think it was a possibility that I could do it for a living.

Of course, you grew up with a bit of showbiz in the family, with your great uncle (the actor Dirk Bogarde).
Yeah. I never got to meet him or anything, but I've seen a few of his films and they were really cool.

A lot of people will have first come to your music primarily via your cover of Bon Iver's Skinny Love in 2011 . . .
I'd never really done covers before, so the idea of interpreting someone else's song was something completely new to me. Then Skinny Love was played on the radio by Fearne Cotton, which was so exciting, and it started to build on YouTube after that. I remember being at school at the time and not being able to concentrate on anything.

Your first album was mostly covers, but you've been writing your own material for a long time.
I started writing when I was eight. It's always been the aim to do an album of all originals, so Fire Within is very special for me. I can't remember what the first song I ever wrote was called, but it was really sad – it was about love and a break-up or something. Yeah, I was a serious eight-year-old (laughs).

Do you think releasing a covers album as your debut made it more difficult to establish your own material?
No, definitely not. It was the right thing at the time and it really opened a lot of doors for me. And I learned so much just from interpreting those songs, too; the different ways that each song can be written, how production and instrumentation can add so much to a song; stuff that I'd never really thought about before. When it came to releasing Fire Within I was so nervous; no one's heard my writing before, so it was definitely scary. But I think it worked out well and I'm happy and proud of it.

Has your age ever impacted negatively on your career?
No, I've actually been really lucky with that sort of stuff, I think – especially when it came to working on the albums. To me, it's all about the music, so I've been lucky that people haven't really treated me differently because of my age. I'm definitely a fan of people like Lorde, for example; it's nice to know that people my age are doing music and are making a success of it.

What are all of your schoolfriends up to while you're selling out gigs all over Europe?
I guess they're all at college at the moment. But I'm very close with them, still, which is really nice. I see them all when I'm home.

You've been pretty busy with your career since the age of 12 – do you feel that you've sacrificed some of your "normal" teen years, in a way?
No, not at all. There are always times that I hear about a party going on at home with friends, and that sort of stuff, but I get to do that when I'm home and I see them a lot. My parents actually used to travel with me for the first two years, so I always had a piece of home with me, too, which was nice. I just feel that I'm really lucky to get to do what I love.

There's been a lot of talk in the media about young musicians lately, with the various escapades of the likes of Justin Bieber and Miley Cyrus. Is it easy to become wrapped up in that surreal showbiz world?
I just try and focus on making music and that's what it's about for me. I don't feel any different to two years ago, really. I guess it's different for me because I still live in a small town in the countryside, so it's quite a change to travel and to see all of these new places. But my head's still at home, really.

So there's no crazy backstage parties, swinging naked on wrecking balls, anything like that?
No, nothing like that. I'm very boring.

You've already achieved so much: a Grammy nomination, performing at the Paralympics opening ceremony, working with people like Ryan Tedder, Sia, T Bone Burnett. What's left on your to-do list?
God, I don't know. I never really think about the future too much, it's too scary (laughs). I'd love to play some festivals, like Glastonbury, just because I haven't done really many yet and it's such a different feel to a show. The audience is so alive and moving all the time, and changing, and I love that idea.

Is there anybody that you'd really like to work with?
Gosh, there's loads of people. I've always been a huge fan of Tracy Chapman's, I've grown up with her music. I'm a huge fan of KT Tunstall and Paolo Nutini, too. And a band I love at the moment are Kodaline, who I believe are Irish.

Looking back, what advice would you give to your eight- year-old self?
Umm… I think just to keep writing and being original, and get your stuff out there. That's about it.

Birdy plays Vicar Street, Dublin, on March 2nd. Fire Within is out now