Two years on from the release of her debut album, The Family Jewels, Welsh-born singer Marina Diamandis’ voice is muffled with sleepiness as we talk over the phone. She greets me cheerfully, yawning and then laughing as she apologises, “I am in England, where it is still very early, where it is raining, as usual, and where I am sitting in bed, still in my pajamas. Which sounds a bit lazy, really, but it’s not very nice outside and my bed is so warm!”

Who can blame Diamandis for taking her quiet time when and where she can get it, especially given how much in demand she is these days? Since the recent release of her sophomore album, Electra Heart, she has topped the UK Albums Chart and will soon support Coldplay on a string of European tour dates, playing massive stadium venues, before mounting her own solo tour next month in what she sardonically tells me are “smaller places. I can’t really ever imagine headlining one of my own shows at a stadium, can you?”

She had been slated to tour the UK earlier in 2012, but those plans were thrown into disarray by what she describes as “the boring singer thing: throat problems. The doctor basically told me I had to shut up and couldn’t sing for the length of an entire concert or I risked permanently damaging my voice, so I thought I better actually listen!”

For Diamandis, the last two years have been a time of immense personal and musical growth. Though her debut album reached number 5 in the UK and garnered significant critical acclaim in the US, its sound was markedly different to the multi-layered dark pop aesthetic that pervades much of Electra Heart’s 16 songs.

That shift, from the independent scene to the more mainstream pop one, was entirely deliberate on Diamandis’ part and something she admits she initially struggled with. The album is, she says, “in two parts, really: one of them really reacting against being seen as a victim and the other much more raw and exposed.”

“Because I was making this jump, there was a point in time where I feared that would equate to me seeming or sounding vapid, you know? I was constantly trying to justify this change in direction, to myself and to my fans and to other people around me. I was afraid of seeming to lose any credibility because there always seems to be an argument that some pop music isn’t credible, that it doesn’t have any depth or any real substance to it,” Diamandis muses.

“And, yeah, there’s definitely a lot of kind of glossy, shallow, disposable stuff out there but there’s also a lot of great, meaningful, really well thought out and well considered stuff out there too. I was worried about my fanbase thinking that I was totally changing and getting annoyed or alienated. I mean, I had no real way of assuring people that what I’d done would work out and so all of that stuff was really weighing very heavily on my mind.”

Diamandis wrote and recorded much of Electra Heart while living in the US for an extended period of time, most of which was spent in Los Angeles.

It is a country and a culture that has long intrigued her, an abiding and deeply felt fascination that was evident on The Family Jewels but has, for a second time, bled into almost every aspect of the new album’s conception, writing and recording.

In the lead-up to the album’s release, Diamandis began posting videos on YouTube that revealed not only new songs but also the vehicle she says she created in order to write and record it. She describes the videos as “little films. They’re mini-films, really, kind of parts one, two and three, and the vehicle for the archetype. It is quite camp, visually. I watched Valley of the Dolls an awful lot and I think it shows!”

“It’s quite hard for me to explain because she, Electra Heart, is more a figure who portrays, and kind of epitomises and also embodies, I guess, the lies and illusions and the whole American dream thing. There’s a bit of Greek tragedy to it. It’s something that really fascinates me about American culture, that entire notion that it doesn’t matter who you are, or where you’ve come from, you can go away, you can do anything, you can completely reinvent yourself, you can become anybody and rebuild yourself in some sense. That’s why I think I find it alluring. As an artist, I think that’s really good, fertile ground to be creative in,” Diamandis says.

“I recorded 10 songs in California, between Santa Monica and Hollywood, and then I had two songs that I wrote in London, in my bedroom, so most of it was written there. ‘Teen Idle’ I wrote in a hotel room, off Hollywood and Vine, I was living in quite a nice hotel, actually, for about three months, but even though the hotel itself was nice it was in what was a really skuzzy part of town! That turned out to be quite perfect, really, and I suppose, all of the clothes I was buying was very kitsch and very 70s. I remember buying this bright pink PVC dress at a vintage store in about April of 2011 and it was kind of from there that entire vision for the album began forming. If I hadn’t actually been living in America and immersed in American culture then I think I’d have made a very different sounding album.”