The scene outside the window of Lady Sovereign’s tour bus is evidently straight out of Night of the Living Baseheads, with the crack-addled addicts of Philadelphia making it clear that America’s War on Drugs isn’t going any better than its War on Terror. As a stranger in a strange land, the English MC is understandably fascinated. She’s also pissed off, although for different reasons. What’s got the Biggest Midget in the Game in fighting mode is the fact that her past has, unexpectedly, come back to bite her in her self-described “non-existent bum”. On her just-released, Top 10–worthy Public Warning, the five-foot-one Londoner casts herself as rap’s newest original prankster. But as she mounts her first major assault on America, there’s sniping that the artist also known as S.O.V. hasn’t always come as currently advertised.

“When I first started, it was more on the dark side,” she reveals, sighing heavily before continuing: “But…whatever. There’s a really embarrassing thing on YouTube right now which I just found out about yesterday. There’s this infamous film, X-ed, that I did about four or five years ago that’s on there. It’s from my very, very early days when I was shit. I used to have some really stupid lyrics like ‘I’ll come and hunt you in a balaclava and stab you’ and shit like that. It’s all bullshit because I’m not that kind of person. But back then I was young and immature and, I suppose, stupid.”

If nothing else, the X-ed clip proves that Lady Sovereign didn’t become hip-hop’s latest saviour overnight. Long before she was signed by Jay-Z, who inked her to the cred-boosting Def Jam Records, she was known simply as Louise Harman. Raised by working-class parents in London’s decidedly blue-collar Chalkhill Estates housing project, the emcee admits that she wasn’t exactly marked for greatness as a kid.

“By the time I got to high school, I was a bit of a loner,” Sovereign says. “I ended up getting kicked out. Because of that, I left high school without any friends. But even though I was a loner, I was loud, obnoxious, and I stood out.

“I would stay at home rather than going to school,” she continues. “Not purposely to write lyrics, but more to get away from people for a few hours a day.”

If you want to know more about Lady Sovereign’s private life, look no further than Public Warning. Built around deliriously woozy horn loops, “My England” sets things up with “I ain’t about tea and biscuits, I’m one of those English misfits/I don’t drink tea I drink spirits, and I talk a lot of slang in my lyrics”. The reflective funk-lite jam “Those Were the Days” turns the lyrical microscope on her Chalkhill Estates childhood with “Used to race down the hill in old Safeway trolleys/I wasn’t indoors playing with Barbies or dollies”. And the dizzying “Blah Blah” gives you an idea of the kind of questions S.O.V. endures during interviews with “people wanna classify me as an Eminem”.

Lady Sovereign likely doesn’t want to hear it, but she has more in common with Marshall Mathers than skin colour, undeniable lyrical dexterity, and often-stunning skills on the mike. Looking back, Eminem’s smartest career move was positioning himself as a self-deprecating joker on his debut, The Slim Shady LP. Humour is a potent weapon and, like the Beastie Boys before him, Eminem used it to crash hip-hop’s colour barrier. Playing the cutup also looks like it’s paying off for Lady Sovereign. ?It’s not lost on her that English MCs haven’t exactly made America forget about Kanye West, 50 Cent, or, for that matter, LL Cool J; as much as they’ve been embraced by North American critics, Dizzee Rascal, M.I.A., and the Streets’ Mike Skinner remain cult curiosities on these shores. Unlike her countrymen, Sovereign doesn’t appear to take anything seriously, and that’s paying off in America, where England seems to exist primarily as something to be lampooned by the writers of Saturday Night Live. Propelled by the played-for-laughs first single “Love Me or Hate Me”, Public Warning has already made an impact stateside, hitting No. 1 on MTV’s Total Request Live, something no other British artist has achieved.

There’s another reason for her initial success: as much as she got her start in the U.K. grime scene, Public Warning shows that she’s outgrown her roots. Her flag may be planted in hip-hop, but Lady Sovereign isn’t afraid to deviate from the genre’s standard blueprint, incorporating everything from sepia-toned jazz, 2-tone ska, and spirit-of-’79 new wave into Public Warning’s 13 tracks.

“I grew up listening to hip-hop, garage, and grime,” the 20-year-old says. “I’m older now, though, and I understand good music for what it is. When I was younger, things like ska used to scare the living daylights out of me. I called it clown music. But I appreciate it now. There’s so much music that I like—as long as it’s original, I love it. And yes, all that different music works its way into what I’m doing now.”

For all the confidence she shows on Public Warning, Lady Sovereign wasn’t born the Biggest Midget in the Game.

“I used to take criticism really badly—I did a lot of crying when I was 14 and 15,” she confesses. “I wasn’t sure what I was going to do with my life, so what other people thought really affected me. But I got better at this, and now I wouldn’t change it for the world.”

Given that she’s such an anomaly in hip-hop—English, female, and white—it’s only fitting that S.O.V.’s ultimate goals don’t include cases of Cristal, imported sports cars, or Snoop Dogg–brand pimp chalices.

“I wanna be happy, and that’s about it,” she says simply. “Things like cars and houses, there’s no point lying—I’ll gladly have all that. But they aren’t important. The only reason I’d want money would be so I could take care of my friends and stuff. Mostly I just wanna have a laugh, for the rest of my life.”

With Public Warning, Lady Sovereign is already well on her way.

Lady Sovereign plays the Commodore on Friday (November 10).