As fans of X Factor will of course know, former judge Cheryl Cole joined current judge Gary Barlow as his assistant during this year’s Judges’ Houses round…

And of her input in helping him choose which acts should go through to the live shows, and in her advise to his artists, Gary described her presence as “invaluable.”

Speaking to the Daily Star, Gary – who held his Judge’s House round at posh Boughton House in Northants – said, “It was brilliant to get her, she is A-list.

“I said to her, ‘No pressure at all but I’d love you to come and be my guest judge’.

“We’ve always been quite close and when we did the Jubilee together, I thought, ‘I wonder if she would’…

“I knew it would be great for my acts to be watched by someone who has so much experience in this competition. That’s invaluable.”

Gary went on to say that being a judge and mentor on the X Factor is harder than performing at Wembley or at the Olympics closing ceremony, when he of course sang with Cheryl.

He said, “When I wander on stage at Wembley or the Olympics I’m all right, I’m cool.

“I’m not nervous because I know what I’m doing, and it’s me.

“But when your act is going out there, it’s like they’re your kids.”

The fact that Cheryl joined Gary at Judges’ Houses came as a surprise to nearly everyone, since it had been expected that his Take That band mate Robbie Williams would, as he did last year, assist Gary.

And according to a recent report in the Daily Mail, not even X Factor boss Simon Cowell knew that Gary had asked Cheryl to help him out.

The paper states, “The plans were so cloak and dagger that Barlow went to the extent of making people believe that Robbie Williams would be he surprise mentor.”

An X Factor source told The Sun, “Only Gary’s intimate inner circle know.

“He hasn’t even discussed it with Simon or ITV bosses. It’s been seriously top secret stuff.

“They’re all under the impression it’s going to be Robbie. No one even noticed the dates for the recording clashed with Robbie’s new solo tour.”

But when asked if Cowell was angry about his secret plotting with Cheryl, Gary said, “He’ll be happy because it will bring viewers to his show.

“He’ll be loving it.”

Gary apparently asked Cheryl to join him at Judges’ House as the pair relaxed over a drink following their duet at Buckingham Palace in June for the Queen’s Diamond Jubilee.

Cheryl recently told chat show host Jonathan Ross that although she’s in contact with Simon, they are far from being as close as they once were.

She said, “I do talk to him every now and again. We’re frenemies.”

As to the other judges, Ne-Yo assisted Nicole Scherzinger to make her decision about the Boys while Tinie Tempah helped Tulisa make up her mind which of the Girls would go forward.

And of course, Louis Walsh, who’s mentoring the Groups, was joined by another ex-judge, Sharon Osbourne in Las Vegas.

Here’s a reminder of Gary and Cheryl’s duet for the Jubilee concert…