RUMER, whose dulcet Karen Carpenter-ish tones have been ubiquitous on certain daytime radio playlists of late, is one of the less likely breakthrough artists of 2010.
For a start, at 31, she is considerably older than her new female singer-songwriter peers.
She spent most of the last decade trying in vain to kickstart her career both as a solo performer and as a member of an indie band called La Honda.
And unlike those X Factor entrants who pay lip service to their "rollercoaster" of a "journey", her life really has been tumultuous, to the point that it almost proved her undoing: her mother had an affair with the family's Pakistani cook while they were living in Islamabad and none of her seven siblings knew she had a different father.
In the fallout, her parents got divorced and Rumer, born Sarah Joyce in 1979, grew up a depressive, anxious child. In her early twenties, her mother died of cancer and, on the brink of a nervous breakdown, she went to live on a commune on the south coast of England for a year. It was only when she met the man who would become her producer, Steve Brown, that her life turned around.
It's another unlikely element of the Rumer story: the indie girl with one Rough Trade seven-inch single to her name, teaming up with the stalwart of mainstream entertainment.
Brown had been working in musical theatre and TV comedy for years – he was Alan Partridge's gay bandleader Glen Ponder on Knowing Me, Knowing You and he's collaborated with everyone from Ant and Dec to Harry Hill – and yet he had never produced anyone before. Nevertheless, when the two met, it felt like kismet, albeit without any of that word's romantic connotations.
"People took the piss out of me when they found out I was working with him," admits Rumer in the London studio where she recorded her debut album Seasons Of My Soul, as Brown looks on and laughs.
"Musicians I knew said, 'You've got to be joking! What's he done?' I couldn't explain it scientifically – we were at opposite ends of the spectrum."
There's a song on the album called Saving Grace that goes, "You truly changed my world... You take my hand, you make me strong". It could almost have been written about Brown. They are as comfortable around each other as an old married couple, and there is gentle ribbing. She tells me that one of the phrases she has coined is "STFU" which stands for "shut the f*** up" and is designed to curtail Brown's often lengthy digressions (another is "Corbett!" as in Ronnie, the comedian renowned for his interminable anecdotes).
Meanwhile, he moans about the things on his remit that aren't necessarily the province of the producer such as "having to pick chewing gum off her jeans, and zipping and unzipping her for gigs".
The respect they have for each other's contributions, however, is considerable. Rumer calls Brown "the British Sondheim" and proudly shows me a letter of praise pinned to the studio wall, which was written by the celebrated US composer after he'd seen one of Brown's musicals. "I'm his PR," she jokes. "Harry Hill calls him 'the best-kept secret in showbiz.'"
Rumer's route to Brown's studio was circuitous, not to mention costly. "I spent thousands of my mother's inheritance on cowboy producers. Projects were started and not finished. I tried everything: folk, country, whatever. But the music really wanted to be epic and sweeping and widescreen because that's how the songs were written."
In Rumer's mind, the arrangements were as lavish as the classic American musicals, and only Brown could realise that vision.
"All those fantastic songwriters – Gershwin, Rodgers & Hammerstein, Jerome Kern, Irving Berlin, Johnny Mercer – with their beautiful lilting epic melodies... that's what I'm about, and Steve knew how to achieve that. My songs are visual, theatrical. They're stories with atmosphere, emotional landscapes that need a lot of expression."
Rumer was stuck in the latest in a long line of menial jobs – working at the Apple store in London because she has always been "into technology" – when she met Brown.
He caught one of her acoustic troubadour sets at the Cobden Club and, impressed, invited her down to his studio. Rumer remembers being "uptight", while Brown "sensed that she'd been burned and would take a lot of time to trust me".
As soon as she began playing and singing, he knew this was something special. "She blew me away," he recalls.
"It was epiphanal. I was moved to tears. It chokes me up to think about it now." Rumer is equally emotional. "We both did a lot of crying throughout this process," she says.
What impressed Brown was Rumer's uncanny musical sixth sense, which made up for any lack of virtuosic prowess.
"There are lots of people with masses of technique," he says, "but what Rumer has got is that she can convert personal experience and turn it into musical expression. She might not know all the chords or what a flat fifth is, but there's something guiding her that is totally intuitive."
Rumer has been acquiring numerous high-profile fans recently. In September, after she performed three songs on Later... With Jools Holland, Jake Shears of Scissor Sisters was effusive in his praise, as was Sandie Shaw.
Carly Simon invited her to spend the summer at her home in Martha's Vineyard.
"She was a firecracker," says Rumer. "She was everything you'd want a legend to be: glamorous, fun."
Burt Bacharach was another convert: cue another invitation to the home of a giant of American song.
"That was profound," she says. "I stood in his lounge and sang for him, and he went, 'Wow, that's amazing!'" Bacharach was so impressed, in fact, that he provided her with a song that, full as it is of allusions to snow and Christmas, might see a release next month.
Brown plays me an unfinished version of Some Lovers: even without the flugelhorns and sleigh bells that he and Rumer want to add, it is classic, wintry, bittersweet Bacharach, with the gorgeous plus of Rumer's vocals.
Another accolade has come from Elton John, who asked Rumer to be his and Leon Russell's special guest during their BBC Electric Proms concert, last week.
"I'm thrilled about it because it's a proper vote of confidence," she says. But arguably the surest sign of Rumer's arrival came in September when, after tweeting his approval of her, the Guardian commissioned former deputy PM John Prescott to write a blog about her.
"Like Billie Holiday, there (is] real sadness and longing in her voice," he wrote. "Burt Bacharach and Elton John have already become firm fans. Well, you can add me to that list." She could hardly believe it.
Then Rumer tells me about a card that Harry Hill gave her recently. "On the front it said, 'My Life Is Crap'." And on the inside? She smiles. "'Not Any More!'"
The album Seasons Of My Soul is released by Atlantic tomorrow
This article was first published in Scotland On Sunday, 31 October, 2010