“It’s weird I know, but sometimes it feels like something outside myself. It’s not necessarily that a lyric is even something that’s happened to me but I almost feel like it has because I can get swept up by the emotion, and when I do it can be overwhelming.”

Big emotions and sweeping, widescreen melodies form the beating heart of her much-anticipated new album ECHO, which sees her re-teaming with the likes of Max Martin, Ne-Yo and John Shanks as well as working with new collaborators Xenomania and Julian Bennetta. Direct, incisive song titles like BRAVE and BROKEN cut to the chase, setting emotions-laid-bare lyrics to timeless yet utterly contemporary soundscapes. And with Leona co-writing several tracks on the album, they are more quintessentially her than ever before.

“I really wanted a dramatic, almost filmic quality to the songs,” says Leona, a self-confessed ‘film nerd’ who unexpectedly name checks 80s fantasy The Labyrinth as her favourite ever flick. “We would even put on movies on in the studio to inspire us, it was a cool way of writing. I’m always thinking of scenes in my head.”

While Leona readily admits she is well aware of the expectations on her in following up her 6 million plus selling debut SPIRIT, she wisely focussed on putting that out of her head and just creating great songs – none more so than spine-tingling lead single HAPPY, co-written with Leona’s old BLEEDING LOVE compatriot Ryan Tedder. Rising from a fragile, almost acapella intro, a gorgeous piano line carries it to an anthemic life-affirming chorus featuring a gravity defying vocal performance from Leona.

“That vocal was totally spontaneous, I sang it down as soon as we finished writing, Sometimes it’s better not to overthink things,” says Leona shrugging off any fears of recreating those head-spinning high notes live. “It’s weird because the highest parts of my voice – my head voice - are the ones I actually find easier singing. I was trained in Opera so that comes really natural to me.”

Leona says it was hard to think of a title for the album straight away, but when it finally came it made absolute sense. ECHO not only reflects the record’s ‘epic and ethereal’ sound, but what’s more it appeals to Leona’s innate love of fantasy and otherworldliness – the places she would go in her head as a child ‘to escape’ and start creating the songs about other worlds, other lives.

“Echo was a nymph in Greek mythology and she fell deeply in love with a boy who didn’t return her love,” she recounts. “ But she loved him so much that she pined away till only her voice remained. That’s a really sad and beautiful story.”

If there’s a whispy, head-in-the-clouds quality to Leona at times (she’s currently besotted with fashion icon Vivienne Westwood she says because of the period references in her work – “if I could walk around in period costume all day I would”) it’s more than countered by a certain steely determination at her core. Don’t forget – when X Factor was just a shimmering Emerald City on the horizon, this girl would spend her days working in a succession of part-time jobs (“oh, everything receptionist, Pizza Hut waitress, there were loads”) to fund her fledgling night time studio sessions and confidence building early gigs around East London.

“I think sometimes people mistake shyness for someone that doesn’t have motivation – but I have so much motivation,” she states. “I’ve got a lot of ambition and drive – it probably comes from my parents being really supportive of what I want to do and knowing in life you have to work for what you want.’

It’s that quiet but resolute determination and complete focus on her craft that has seen Leona rise in a few short years from gigging around Hackney to sharing stages with the likes of childhood idols Beyoncé and Mariah Carey (“When they asked me I was like ‘are you serious? I can’t believe these people even know who I am”). You saw it in 2006 when week after week she returned to the X Factor stage and belted out pitch perfect takes on standards like ‘Summertime’ and ‘Over The Rainbow’. No frills or gimmicks - just that voice. Now, having spent the summer in the Hollywood Hills, LA (somewhere definitely not on her old number 55 bus route from Hackney) she’s been turning down invites for swanky celebrity dos to spend hour upon hour in the studio perfecting and polishing ECHO.

“I’m sure there are people out there who embrace everything and go to every party and that’s fun from time to time, but to be honest I’d much rather be in the studio or at home with my boyfriend or my family. I think that’s what keeps me grounded.”

This is a girl who still lives round the corner from her parents in Hackney (“paparazzi don’t come to Hackney, it’s only when we go to Islington,” she jokes) and has had the same steady boyfriend since she was 17 (they first met when she was 10). One of her few indulgences is frequent – as frequent as her schedules allows – horse-riding sessions in the countryside where she is free and left to her own thoughts (Leona is great animal lover and tells an odd but utterly sincere story about buying a baby rabbit from a homeless man in LA. The rabbit now lives with her and is on nodding terms with Ne-Yo).

In the increasingly here-today-gone-tomorrow world of fame hungry wannabes selling their privacy for column inches, she is that rarest of creatures, an old school star with integrity.

“I was asked to open the Harrods Sale this year but I had to refuse. My principles mean a lot to me. I’m a strict vegetarian so I don’t think fur should be sold in any way,” she states. “It’s about time everyone came up to date with their attitude towards the fur trade.”

Vivienne Westwood’s strong, ethical stance is one of the reasons Leona has turned to her for the understated glamour of her punk couture look for her return to the public eye. That and the fact that “she’s British, and I like to support Britain… oh, and she does great corsets”.

Even so, in typical Leona fashion, she quickly adds that you’re as likely to find her rummaging through the racks of Miss Selfridges or New Look (“great for vegetarian shoes” apparently) in Oxford Street as you are in the swankiest designer stores.

But for now, all Leona’s energies are focused on the imminent release of ECHO to an eager public. So eager in fact, that the recent much-reported illegal leaks of certain unfinished tracks have formed the highest profile case of its kind. Second time around, the stakes may seem even higher but with typical understated self-assurance Leona seems quietly undaunted by it all.

“I’m actually more confident with this album than the last. I’ve taken more control this time and I feel more at ease with everything. To me, it’s all about great songs and I hope the songs move people as much as they move me. I hope so anyway.”