Banal yet brilliant, cutting yet corporate, Katy Perry occupies a strange place in the pop sphere. 2010's Teenage Dream was only her second album but it turned her into a chart juggernaut. From California Gurls through to Firework and then two huge hits from a reissue, Perry ended up with 6 number ones on the US' Billboard Hot 100, the kind of staggering feat that comes from a heady mix of big tunes, big marketing and a star relentlessly out to up their pop game.
