It's probably just as well that Cheryl Cole was decked out in military garb when she appeared on The X Factor recently -- she's set for the mother of all chart smack-downs with none other than Irish Girls Aloud pal Nadine Coyle.

Glitter and eye-liner are set to fly as the band mates get ready to square off. In one corner is Cole, Britain's so called 'Angel of the North'; in the other, Derry-raised Coyle, widely acknowledged to be the real vocal talent in Girls Aloud. It's like Blur vs Oasis, with better dancing and -- so the gossip industry hopes -- lashings of extra bitchiness.

Rumours of strained relations between the two are rife. It's been widely reported that Coyle isolated herself from her Girls Aloud band mates by relocating to Los Angeles several years ago.

And while the rest of the group were in studio to cheer on Cole's X Factor performance, Nadine was too busy putting together her own solo album, set for release early in 2010, to attend -- a slight at which Cole is said to have been a little miffed.

Of course, you can hardly blame Cole for wanting to outshine her band mate. For the entire history of Girl's Aloud she's had to play second banana to Coyle and her human-hairdryer vocals. In concert, Girls Aloud have all but become a Nadine solo show. When they played Dublin earlier this year, it was Coyle who hoovered up all the attention -- with "Chezza" and company reduced to glorified backing singers.

Then again, Cole is clearly far more adept at the dark arts of self-promotion. With Coyle out of the picture in LA, she has been cannily building an alternative career as national sweetheart. Stepping in for Sharon Osbourne as an X Factor judge, Cole has demonstrated that her true talent may lie in her ability to spontaneously blub in front of the TV cameras -- scarcely a week goes by without Cole bursting into tears, usually because she's just got into a tiff with Simon Cowell again (oddly, little of that wholesomeness is evident when she lays into Dublin twins John and Edward Grimes).

With war clouds gathering, Cheryl has been first out of the traps with a 300,000-selling No.1 single, 'Fight For This Love', and a lavishly hyped debut album, 3 Words ("those words being 'complete effing s***'" quipped at least one reviewer). Seeking to put a slinked- up cyber-babe twist on her wholesome image, Cole has also been vamping it up for the cameras -- critics have derided her attempt to come across all Lady GaGa as resembling nothing more than a very expensive aerobics video.

Simultaneously, she's been hard at work manicuring her media profile, speaking at length about her difficult childhood, her family's multiple battles with alcohol and drug addiction and her own determination never to fall into the same trap. Not that she really needs to lay it on quite so thick -- ever since it was suspected that husband Ashley Cole might be following in the long tradition of love-rat footballers, Cole has been able to count on the sympathy of the UK population.

That's despite a tempestuous past. In 2003, she was convicted of assault occasioning actual bodily harm after a tussle with a nightclub attendant in Guildford (the attendant claimed Cole had racially abused her -- something she denied and of which she was cleared by the court). Nothing in her career has been more remarkable than her success in turning her image around. One newspaper hailed her as 'the Vera Lynn of our times', a reference to Britain's cherished wartime singer who raised national spirits during The Blitz.

Coyle, in contrast, has been notably low key. In part, that's understandable considering she lives on the other side of the world and is very much focusing on the US market (her first release, a cover of Take That's 'Back for Good' recorded with Philadelphia r'n'b group Boyz II Men, has already been leaked on the internet while a Twitter posting revealed she was working with Katy Perry/Aerosmith songwriter Desmond Child). Whether focusing on the music and leaving the job of buttering up the media to her record label's PR department pays off remains to be seen.

If the two have anything in common, it's a chequered romantic life. Back when she was plain old Cheryl Tweedy from the wrong side of the tracks in Newcastle, Cole dated a sometime drug user, who subsequently sold his story to the tabloids, claiming that his ex-girlfriend had helped wean him off heroin.

Then there was the controversy about Ashley Cole, accused by the press of going home with a hairdresser after a night on the town (he denied anything untoward had happened -- and Cole insisted she believed him, but then stopped wearing her wedding ring for a time).

For her part, Coyle has gone through her share of controversial boyfriends. As a teenager in Derry, she briefly stepped out with the son of future Northern Ireland second minister Martin McGuinness. Later, there was a long-term relationship with another home-town squeeze, Neil McCafferty, a professional soccer player with Northern premier league team Dungannon Swifts.

Following that, she got together with bad-boy actor Jesse Metcalfe, best known for playing hunky gardener John Rowland on Desperate Housewives. A young man in the fast lane, Metcalfe fell prey to some familiar Hollywood vices and entered rehab for alcohol abuse in 2007.

When he was subsequently pictured on the arm of another lady, he was accused of cheating on Coyle. However, in an interview with Miriam O'Callaghan, she insisted the relationship had already ended. She's since hooked up with American footballer Jason Bell, a solid, if slightly dull, opposite to Metcalfe. So, who will win this musical mud-wrestling contest? The smart money -- by which we mean the bookmakers -- is on Cole. Paddy Power is offering odds of 4/6 that Cole's debut solo single shifts more units than Coyle's. "I think when it comes to Cheryl and Nadine, it's definitely Cheryl who is coming out on top," says Jennifer Stevens, editor of U Magazine, which has run several cover stories on Cole.

"When the band were together it was automatically assumed that it would be Nadine who would have the bigger solo success, what with actually being able to sing. But Cheryl's fought hard and her personality, TV presence and friendship with Simon Cowell have all served her very well.

"I guess who is the better singer is irrelevant at this point especially in the world of highly produced pop. And her recent signing as a face of L'Oreal Paris cements her as probably the biggest star in the UK right now. Which doesn't really leave Nadine with much.

"All she can really hope to do is break the US -- the holy grail of celebland, but right now Cheryl is Queen of all and Nadine runs a chain of Irish bars in California and that's got to hurt."

Irish Independent