'The X Factor' judge - who helped form the girl group on the reality series 'Popstars: The Rivals' in 2002 - claims the Derry-born singer, 27, is the best vocalist in the group and would have been a bigger star if she married a footballer.
The 60-year-old music mogul also hit back at comments made by 29-year-old member Cheryl Cole - whose solo career took off after she divorced Chelsea footballer Ashley Cole in 2010 - in her recently released autobiography in which she dismissed his early role as their manager.
He told the Guardian newspaper: ''You want the real story? OK, I'm going to tell you. There was a girl in Ireland called Nadine Coyle, and I said, go for this show. She is an amazing vocalist. A real real singer. So I pushed her in the band, and I said Nadine is the lead singer.
''I never worked with them very well 'cos they kind of scared me, the five girls together. Five girls! Five girls is a bit scary. They were all a bit scary. Generally, girls don't like each other. That's the problem. I couldn't help them with their hair, makeup, all those things. And from the moment I said Nadine was the best singer, the others alienated me.
''Well, she is the best singer! By a mile. But she didn't marry a footballer. If she'd married a footballer she'd have been a big star.''
Girls Aloud - whose members also include Sarah Harding, 31, Kimberley Walsh, 30, and Nicola Roberts, 27, recently reunited after a three-year hiatus - performed their new single 'Something New' live for the first time on Children In Need on Friday night (16.11.12).