As soon as you heard the tune, you knew that you'd chanced upon something special. In what was an otherwise depressing, distressing year for radio pop, this record seemed beamed down from another, better, sexier planet. A lurching, slashing, nasty rhythm, somewhere between dubstep and grime. An evocation of both the pleasure and the danger at the heart of the best club nights out you've ever had. And, crucially, a girl's voice. This voice was high and pretty, yet strong and indomitable. It was somehow urban, and pop, and soul and slightly alien. Apparently, the voice was called Katy B. And it was, indisputably, "Katy On A Mission."

The maker of "Katy On A Mission" is not a celestial alien... at least, not today. Today she's a small, friendly and alarmingly pretty Peckham lass who is getting her hair done in a small room at the Rinse FM HQ in East London. We're also joined by her mentor and producer Geeneus, who is also the co-owner of the legendary London pirate station which finally got its long overdue broadcasting licence in June 2010. He's going to help his protege explain how a BRIT school graduate with a couple of garage tunes to her name has become the maker of a classic underground breakout anthem and, in the forthcoming "Katy On A Mission," one of the most eagerly-awaited dance albums of recent times. It seems like overnight success, but actually took over three years. And Katy is still just 21.

It all begins back in Peckham. The young Katy was an R&B loving girl who wasn't satisfied with just listening to her favourite Boyz II Men, Destiny's Child and Alicia Keys records. Her parents were supportive of her ambitions for a musical career, and sent her to The BRIT School. Her soul fan father had been a singer himself, and various aunts and cousins were musicians. Hanging out with like minds at School led her into an enduring love for neo-soul, particularly Erykah Badu and Jill Scott.

But any London kid who loves urban music is unavoidably surrounded by the sounds of the UK underground. Apart from listening to pirates like Rinse, she also had classmates who were making their own grime and garage tunes. You know all those BRIT graduates who cough uncomfortably when the name comes up and try and pretend they grew up in a sewer and learned to make music among feral wolves, or somesuch? Katy isn't one of them. "Do you know what? I'm so happy to talk about the BRIT School and everything. Because some people seem to think it's some kind of fame school, but it's not like that at all. I went there when I was 14 so we did normal lessons. Music is just a small part of it. But the atmosphere is just amazing. People actually enjoy going to school. The journey that you go on in such a small period of time... and the people that I met there are still my best friends today. They have a really good studio there and that's where I got my first demos done."

Katy went on to a degree in music at Goldsmith's in New Cross, south London. Her time there included full band, orchestra and choir performances of The Beatles' Sgt Pepper at Abbey Road and Glastonbury. "It makes you realize what goes into being a musician... how to rehearse, how to create a performance. And for a singer it really helps to study theory, understand music, and know what you're talking about. Singers often go into a room with musicians and get intimidated. They'll talk to you like you're an idiot. Knowing as much as them about music gives you a kind of confidence."

Nevertheless, its taken three years of work and experiment to get the album made. "We made one album and completely scrapped it," laughs Katy. "It was like... the warm-up," adds Gee. But... three years? Teenagers aren't noted for their patience. Didn't the slow progress drive Katy nuts? "Definitely. But you've got to understand that Gee and Sarah (Lockhart, Rinse FM co-owner) are busy people. Gee's a manager, DJ, producer, radio station owner, promoter, record-label head. And they do all of it really well. So sometimes I did feel like I was bottom of priorities. But I always had faith that they would do their best. And I'm glad that it's happened now. I got to finish my degree, and 'Katy On A Mission' all happened just as I came out of Uni. The timing's perfect."

The original idea for an album was that Rinse FM wanted to make a showcase for their DJs, most of which are also composers and producers. This would have been multi-genre, as well as multi-artist. In order to give the record any hope of sounding like an album rather than an eclectic compilation, it needed a sonic link. But despite Katy's presence, the eclectic range of producers just didn't link well enough to provide any continuity. Meanwhile, Geeneus and his compadre Zinc were falling in love with Katy's voice, lyrics and melody lines. It became increasingly obvious that Rinse FM's showcase had turned into a potential debut album for Katy B. "It just seemed natural. Geeneus and Zinc were providing the best tracks and I loved working with them."

'It's been a good experience to work with her," Geeneus smiles. "She's down-to-earth, just like us. We'd worked with other singers and they're all a bit, like... diva-ish. As soon as I heard her I knew there was something about her voice. I was writing a lot of grimy music, and the scene was all getting a bit overcrowded with men. We can make ravey bassline music all day long. We needed the girl element back in it. When I've played this album to girls they don't care about the background music -- they couldn't care less. They're like, "Oh... the lyrics." It wasn't planned like that. But that's what Katy supplies. I think we've merged our two worlds into one." Let's be clear: the beats hail from her stellar cast of producers, which also include Benga, Benny Ill and Magnetic Man. But the songs are all Katy's own work. The process honed Katy's fledgling songwriting skills "I come from a background where I would be getting beats to work with. These are people who make instrumental music so there's no song. There's no-one there to write my songs for me. I was kinda forced into it but then found out that I really enjoy it." So much so that Katy is also signed to EMI Publishing as a songwriter.

A12-track fusion of underground beats, pop hooks, soulful sophistication... and that alien something that made "Katy On A Mission" add up to so much more than its parts. What's it all about, then, Katy? "It's me, just as a young woman, partying, relationships... the album's definitely where I'm coming from, experiences in my life and emotions that I've felt. I love Jill Scott because her lyrics are beautiful, but always telling a simple story, in a clever way. When someone writes about love you want to be able to relate to it."

Current single Lights On is another perfect meld of urban dark and femme-pop light, and features the wonderful Ms Dynamite. The Mercury Prize-winning rapper had come into the Rinse studios to work with Zinc and Geeneus at the same time as Katy and Gee were writing Lights On. Gee asked her to try spitting a verse, the venerable MS D agreed, and the rest is history. "This is about two years ago," Geeneus reminds us, "and back then no-one had really heard of Katy and Ms Dynamite was a big thing. So she did us a big favour." "She's been really supportive," adds Katy, "a really lovely person."

As the album developed, Katy also insisted that she moved away from P.A.-style live performance and front a proper band. Her ten-piece live group, complete with horn section, are accomplished enough to pull off a triumphant recent support slot with John Legend and The Roots. It's a long way from early shows doing freestyles over Gee's DJ sets. A tour with Tinie Tempah precedes the release of "On A Mission" in March 2011 with her own tour just announced for April. And for her next album, Katy intends to experiment more with live instruments. "We've got trumpets and keys on this record, but I'd like to bring more of that next time around."

But there's still the small matter of her debut album to deal with before increasingly ambitious musical visions can be pursued. The girl may not want to be a pop star. But she increasingly has no choice in the matter. So what, exactly, is Katy B's mission? "I've always had this, "Who cares about the charts?" attitude. But I've always wanted to be successful in what I do. All I've ever wanted to do is make a living." "We're hoping that people would like some real music for a change," Geeneus declares, proudly. "Something that harks back to Soul II Soul and Neneh Cherry. And, so far, its going quite well."

Katy B chews that over, mumbles something self-deprecating... and then finally settles on the best possible reason for making "Katy On A Mission." A mission that makes considerably more sense than marrying a footballer, or bunking off to live in the jungle. "Because I look up to certain singers, I'd like to be that to someone else. It would be cool if someone's favourite album was a Katy B album. That would be the biggest thing for me."

Responsible Agent Marty Diamond