Rock veteran Rod Stewart has revealed he will make a guest appearance on The X Factor. But the former FACES star has angered TV bosses by letting slip his cameo, as they were planning on keeping it a secret. Stewart was just one of a number of stars linked with the show, including SIR Elton John, Beyonce Knowles and Julio Iglesias. The X Factor producers wanted to keep viewers and contestants on tenterhooks by springing the star judges on them at the last minute - but Rod has revealed all in a new interview, in which he also confessed he gets stage fright when he's on TV. He says, "I'm going to do The X Factor in a couple of months. Those kids have got some guts. I'm used to big crowds, but even when I do TV shows I'm on edge." The Maggie May crooner is expected to join wannabes at the boot camp stage, giving them singing tips and judging their performances. A spokesperson for the show has tried to cover up the gaff by refusing to verify Rod's cameo, insisting, "We can confirm there will be guest judges, but as for Rod, it's just speculation."