The Arctic Monkeys, a group of teenage boys from Sheffield whose infectious guitar chords and acerbic lyrics were made famous by fans’ internet sites, are generating serious sums of money for the more traditional members of the music industry.

Every song from the band’s first album has been available for free on the internet for months. But this week it is expected to become the fastest-selling debut album in UK chart history, creating an unexpected success for retailers such as HMV, for whom January is traditionally the weakest month of the year.