Despite being unceremoniously dumped from the US version of the show, a thick-skinned Nicole Scherzinger was back on her old X Factor stomping ground yesterday.

The former Pussycat Doll - dressed in a LBD - was all smiles as she joined Tulisa, Gary Barlow and Louis Walsh for the fourth day of auditions at London's O2.

But one person not feeling quite so smiley was Gary who was reportedly less than impressed after being kept waiting for an hour by Nicole while she got her make-up done.

Nicole is the latest star to join the panel as a guest judge after Geri Halliwell, Rita Ora and Leona Lewis all did a stint in the judge's chair until a permanent replacement for Kelly Rowland is found.

But it's not been all plain sailing for the guest judges - Gary Barlow revealed that poor old Leona got booed by the audience.

"I think people think Leona’s a bit bland," he told Metro. "But she was great fun, even though she got booed.

"We also had Geri in Liverpool, who was crazy and lived up to expectations and we’ve had Rita Ora for the last couple of days who has been really great."

Gary also hinted that Dannii Minogue is still in the running to return to the show once she's finished filming Australia's Got Talent.

*Crosses everything*

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