Fergie’s hit Big Diana Vickers, who finished fourth in 2008. She performed her latest single,Katy Perrywas next. Dressed in a black cat-suit, she gave a stonking performance of her newie, Firework, complete with enough pyrotechnics to wake up even Louis!

Katy also told Dermot she was angling for a permanent spot on the X Factor judging panel. “I’m just waiting on a call from Simon,” she winked.