The Irish pop impresario, who spent 11 years as a judge before bowing out, urged Simon to get a more entertaining panel on board and return the show to its glory days.

Louis, 63, was on the panel for the show's inaugural series in 2004 and remained in place for years before quitting ahead of the 12th season.

When asked when he thought X Factor's 'golden era' was, the former Westlife manager told British newspaper The Metro: "The first 11 years I was on it. It dipped a little bit last year. Simon Cowell needs to bring back the original format.

"He needs to have a panel who are fun, to bring me, Nicole Scherzinger and Dermot O'Leary back. And Sharon Osbourne. She's fun and Simon has no control over her," he added, in a thinly veiled reference to Simon's relationship with judge Cheryl Fernandez-Versini.

Music industry veteran Louis also urged Simon to ditch the live auditions which he felt didn't work. But he did praise the level of talent in last year's show, and called Louisa Johnson "a great winner".

Cheryl, 32, is noticeably absent from Louis' suggestions for improving the show. But he was full of glowing tributes for her former Girls Aloud bandmate Nadine calling her "the voice of the group".

When asked why she wasn't more successful as a solo artist he offered another barb, "I don't know. Maybe she should have married a footballer", a reference to Cheryl's former marriage to Ashley Cole.

Cheryl wasn't the only singer Louis showed little enthusiasm for. He admitted his favourite member of One Direction were "none of them", dubbing them the "five luckiest guys in the world", and giving all the credit to friend Cowell with making them successful.

The singing contest struggled in the ratings last year (15) and it was reported The X Factor mogul wants Louis to return as a fifth judge to boost viewer approval.

At the time Louis told U.K. talk show Loose Women, "I don't really know. Listen, Simon said the door was open to me. I talk to Simon, you know, and there's a possibility I might end up on the show... There is a possibility. It's up to Simon... I talk all the time to him so I think there's a chance."