Famously blonde heartthrob Niall Horan from One Direction has allegedly been forbidden to change his hair colour by straight-talking manager Simon Cowell.

The teenager reportedly sent a text to Simon asking if he could dye his golden locks completely black, but the frank talent judge replied immediately with a firm "No way."

Simon is worried that a change of style will affect the X Factor finalists' popularity. A source told The Sun "Simon still controls a lot about the band down to the finest detail. Niall was desperate to get rid of his blond locks and go black just for an experiment, like loads of normal teens."

One Direction's rise to fame came as a result of coming third in the 2010 series of The X Factor after being formed on the show. Signed to Simon's record label, Syco Records, the British/Irish boyband's debut single, What Makes You Beautiful, came into the charts at number one and won a Brit award for Best British Single this year. Their debut album, Up All Night, came in at number two and became the fastest selling debut album of 2011.

The band is currently on a worldwide tour showcasing their debut album.