O'Leary appeared on 'American Idol'

Dermot O'Leary has revealed that he appeared on the last season of American Idol.

Simon Cowell flew O'Leary to LA to watch the US talent show being filmed in a bid to convince him to host The X Factor.

Cowell's campaign proved successful, but only after O'Leary had made his talent show debut on the US series.

He told Heat: "(Simon) did say: 'Come out and see how we make American Idol.' That was hilarious. I got in the back of the shot. One of my mates called me up afterwards and said: 'I saw you on American Idol, clapping to a Bon Jovi song! What were you doing?!'"