Robbie Williams and Ayda Field quit X Factor

Robbie Williams and his wife Ayda Field will not be on the judging panel for the next X Factor, the star has said.

In a post on Instagram, the former Take That singer said they would still work with Simon Cowell on other projects.

Williams and Field only joined the show last year. Some fans were initially worried about the US TV actress's lack of experience in the music industry.

But Simon said at the series 15 launch: "Ayda has been a revelation. I mean, seriously, she's been brilliant."

He explained that you do not necessarily need to be an artist or a music manager to be on the show.

"You have to have taste, good instincts, you have got to like people," he said.

"Ayda has seen the music business from a different point of view so she brings a different perspective to the panel. I think she's amazing."

Field said her years spent with Williams had given her enough experience to be on the show.

"I know that I've helped Rob for 12 years now, I've had to pick him up off the ground and lift him up," she said. "I am always incredibly straightforward, I say it with compassion but I stick to my word and carry it through."

Williams filled the vacancy left by long-standing judge Louis Walsh, who quit the show last summer after 13 years.

Robbie said at the time that he hoped The X Factor would boost his future TV prospects.

"Selfishly, for me, I've had the most fun that I've ever had in the entertainment industry," he told This Morning last September.

"It would be incredible to open a new chapter and have this be the start of it. I'm just having a whale of a time. Who knew that I would be a TV personality? I like it though!"

X Factor has gone through numerous panel changes over the years and has suffered from falling ratings although the show is still the most watched for the crucial 16 - 34 age group on Saturday nights, ITV says.