florence welch. with our anthonyroducing florence and the machine. >> reporter: the strumming. harp... the strumming of the harp may be the first thing you notice about florence and the machine. the second will surely be the flame-haired front woman with the al as bass ter skin and hurricane force lungs. there have been few dog days in america for florence welch, who has become britain's biggest female musical export since adele. her debut album has sold 3.5 million copies worldwide. her video, her dog days are over, has been viewed nearly 20 million times on you-tube. >> if you have a rhythm and you have a voice.... >> reporter: you don't just have a voice. you wail. >> i always worry about singing in closed spaces of deafening people. growing up it was just a chorus of shut up, florence, in my house. i annoyed my family so much because it was constant. >> reporter: 25-year-old florence mary welch, flo to her friends, grew up in south london, the daughter of a british advertising executive and an american art histor