Westlife enjoyed a meteoric rise to success since forming back in 1998, despite Simon Cowell making a brutal dig from the get-go. The notorious Mr Nasty - who was well known for his stinging comments on the X Factor - made it clear that he'd never sign the group of Irish crooners.

He even described them as "the ugliest boy band in the world". Chatting to Jay Leno on the Tonight Show in a candid interview that made viewers gasp, he bluntly declared: “I said to the manager at the time, 'Forget it!'

"When they first came along, they were the ugliest boyband in the world. Seriously, like you couldn't get uglier." However, he added that at a second audition, "one of the ugly ones" had dyed his hair blonde and managed to "get back into the group".

"I didn't recognise him but it all worked out fine and they sold about 50 million albums," the Britain's Got Talent judge quipped. Not only that, but the Flying Without Wings singers have tallied up more than a billion views on YouTube.

Their against the odds success were a surprise to Simon, after Louis Walsh opted to take them under his wing. Band member Kian Egan, who triumphed on I'm A Celebrity... Get Me Out Of Here! and was crowned King of the Jungle in 2013, caused further shock earlier this year by saying he "understood" Simon's point.

"I understand where he was coming from because the band that he first saw is not the band that he signed," Kian revealed on BBC Radio 5 Live.

“As time went on, the band changed. There was six of us originally, and then when Louis [Walsh] started managing us, and when we met Simon, Louis started changing people in the band for a while," he continued.

"It only ended up being me, Shane (Filan) and Mark (Feehily) from the original line up. Then we brought in Nicky and Brian, and that was the band Simon Cowell signed.”

However, Kian took a leaf out of Simon's book when it came to brutal barbs, as he went on to name and shame who he thought the "ugly" ones were.

“Nicky and Brian were the ugly ones, because they're from Dublin!" he exclaimed.

Westlife have long since split up, meaning that Kian's cruel comments are unlikely to spark a feud, but the group ended on a high and record sales were phenomenal.

Meanwhile, Simon Cowell recently landed himself in hot water when he revealed the one regret he had about managing One Direction - that he didn't claim the rights to the band name for himself so he could earn from merchandising.

Some viewers of the podcast episode, hosted by Diary of a CEO's Steven Bartlett, were offended, insisting that all he cared about was commercially exploiting the boys - and he was unfollowed by multiple former band members.

However, Simon has since stated that he received a call from Harry Styles after his comments came to light, reminiscing about the "good times" they'd had.

Meanwhile, the music mogul recently vowed he'd toned down his Mr Nasty persona since becoming a dad to ten-year-old Eric, saying he'd realised the tough impact criticism can have.

Yet one fan wasn't convinced, tweeting: "I just don't buy Simon Cowell's PR strategy to project a softer and more caring public image. Not one little bit."