Three years ago, Calvi was heralded as one of British rock music's brightest new hopes with a spot on the BBC's Sound of 2011 list alongside Jessie J and James Blake, among others. The judges weren't wrong. Her self-titled debut album garnered nominations for the Mercury Prize and the BRIT Awards, and she spent much of the next two years promoting it. Now, following the release of her equally acclaimed second album One Breath in October last year, the 33-year-old Londoner is ready to get back on the tour bus.
"It seems like a long stretch, but I really enjoy touring and playing live every night," she says. "The only difficult thing is that I like to have space. I like to be on my own sometimes and you can't always do that when you're on tour, because you're always with people. So I find that harder than travelling.
"It's much more intense than anything you'd experience in a normal life situation. You're literally living with six or seven other people every single day for two months. You're travelling with them, eating with them, spending all your time with them. Even someone who loves being around people constantly, would be like, 'Oh god, I'd like to get changed without having to go into the toilet!'. I'm going to have a better bus this time, which will help."
Calvi is surprisingly softly spoken given her extraordinarily powerful vocal performances. She speaks slowly and gently, and isn't given to elaborating on her answers unless she is asked to. But that quiet disposition shouldn't be mistaken for timidity. The steely resolve and fierce independence that characterise her music is also lurking behind her words, particularly when she talks about One Breath.
"It was quite a turbulent year when I was making the record and I decided not to try and hide that in the music – to let it come out," she explains. "I think it's important as an artist to feel like you're trying to get towards an honest representation of part of you. Not being afraid to be honest in my lyrics as well. It's a liberating feeling because you realise that you can say anything in art or in music – that's the whole point."
Perhaps that willingness to express her emotions in music has some basis in her upbringing. Calvi's parents are both therapists by profession, and while she has chosen to make her living in a very different field, she acknowledges their influence.
"They taught me how important listening is," she says.
"And also being able to express your emotions and be introspective and thoughtful about why you're doing the things that you're doing. They are all helpful tools in songwriting."
Anna Calvi's music is certainly emotional and introspective, and it's from there that it draws much of its power. Does she see it as a form of catharsis; as a way of dealing with her own emotions?
"Yeah, I think being able to express yourself in a way that isn't just words is very freeing and an important way of experiencing and relating to your life," she says. "It has definitely been good for me to have an outlet. I think I have grown as a person."
Calvi found success as her 20s turned to her 30s – not late in life, but relatively late for a 'pop star'.
Has that been a help or a hindrance? "I think it's been a help because I've had time to develop as an artist away from the public," she says. "I'm old enough and mature enough to be able to tell people what I want. I can't be manipulated and told to do something that I don't want to do – I wouldn't stand for it. Perhaps, if I was 18, I wouldn't be confident enough to make those strong choices.
"From the outset, with everyone I've worked with, it's been like, 'this is what I'm doing'. There's been no space for anyone to tell me to do anything otherwise. It's not that I don't listen to advice – you listen to it and if it doesn't feel right you ignore it. That's the way that I have conducted myself and my work. It's what you have to do if you want your music to have a strong, individual vision."
One Breath certainly has that, characterised by that enormous, almost operatic singing voice, a restless, experimental approach to sonics and her trademark guitar playing – her instrument of choice despite the fact that she studied violin. "When I was a kid and heard Jimi Hendrix play, I was really amazed by it," she recalls. "And the other guitarist [I loved] would be Django Reinhardt. The guitar is a lot more fun and I felt that I could express myself better. I enjoy making stuff up – with the violin you're taught other people's music, you're not taught to improvise or write your own music."
Calvi has often cited classical composers as inspirations, as well as pre-rock and roll performers like Billie Holiday and Maria Callas, as well as choral music.
She is only at the beginning of her career and yet on One Breath there are signs that she is already branching out and finding out what she is capable of – the aggressive punk of Love Of My Life, the sparse beats of Piece By Piece, the celestial voices of The Bridge. "I'd definitely like to do something with an orchestra at some point, and explore writing for more classical music or perhaps soul music," she says.
"Hopefully at some point I'll get to do that."