The 40-year-old talent judge has flown to Los Angeles with his wannabes, where he and his Take That bandmate are preparing to cut eight to four in time for the live finals.
Asked why he asked Robbie to help, Gary told The Mirror, “He seemed like the obvious one. I knew he loved the show. He has done since day one. He watches it all, Jersey Shore, all the crap telly, he loves it. And so I knew he was a big fan of X Factor.
“When we were on tour with Take That, I said to him, ‘I need someone for judges’ houses, what do you reckon?’
“I thought he wouldn’t be too into it but he was like, ‘Please let me’. Then he invited me to his house to stay while we do it.”
Robbie says he has faith that Gary can find the next big thing.
“I love the X Factor and I love the spectacle and being entertained but they haven’t got the music right in the past,” he said. “I don’t know if that’s because of the X Factor people or if the pool of songwriters has dried up. But Gary knows what he’s doing.”