The interview was supposed to promote their forthcoming reunion tour in honour of their late band mate, Sarah Harding, who died of cancer three years ago.

Sitting down with Radio 2 DJ Scott Mills, Girls Aloud band members Cheryl Tweedy, Nicola Roberts, Kimberley Walsh and Nadine Coyle, were discussing the set list for the string of gigs, which will also mark 21 years since the group was founded on ITV reality show, Popstars: The Rivals.

But with only weeks to go until ‘curtain up’, it looks like the claws are already out among the four, who last performed together more than a decade ago.

To the total bemusement of listeners the interview quickly descended into chaos, as the women – all now firmly in their 40s – began bickering after an innocuous enquiry from Mills as to whether the band planned to perform any new covers on the tour. A safe enough question you might argue. Bland even.

Nicola insisted they would not, saying ‘I don’t think we’ve got space,’ only for Cheryl to chime in, saying she was keen on the idea.

‘I’ve said it several times,’ Cheryl told Mills. ‘People like it!’.

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Last year Cheryl, Nicola, Kimberley and Nadine went to see Sarah’s mother, Maria Hardman, to discuss putting together a tour in her daughter’s honour

Nadine, who along with Cheryl was seen by many as one of the more tempestuous characters in the group, stepped in to oppose, interrupting to say: ‘I was dead against it. We’ve got so many songs of Girls Aloud as our own. Why do we need to be doing it?’

‘But we can add just one random cover, it’s fun!’ Cheryl hit back.

Mills immediately stepped in as referee, telling listeners: ‘You join as there is a slight disagreement with Girls Aloud in between whether they should do covers or just the hits. We’ll be back after this…’

The exchange was enough to make listeners wonder, if they are rowing like this on national radio, what on earth must be going on back stage at rehearsals?

When the interview resumed, the row was still raging. The girls continued to talk over one another, with Scott explaining: ‘Girls Aloud are here and they’re still discussing whether they’re going to do a cover version or just their hits. Have we come to an agreement yet? We’re going to have to raise hands again.’

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The last ‘tit for tat’ row between Nadine, pictured during the Radio 2 interview, and Cheryl happened in 2013, after the band officially broke up

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Nicola, pictured during the astonishing interview, insisted the band had not planned to perform any new covers on the tour, saying ‘I don’t think we’ve got space’

It was interview gold, but for Girls Aloud fans, it came as an uncomfortable reminder of the feuds and cat fights which ripped their beloved band apart 15 years ago.

And now, as the group prepare to go on their tour in two weeks time – starting in Dublin – those who know the band fear that a rift will once again rear its ugly head as they travel the UK, sharing tour buses and aeroplanes.

‘That interview was very, very telling,’ said a source who knows the band well. ‘They have all been trying so hard to put the past behind them and move on to the future.

‘But now there are worries this will prove impossible. The betrayals ran deep and nobody involved in Girls Aloud ever thought it would mend but miraculously it did.

‘They have really tried but if a spat like that can start on a radio show, you can only imagine what people are worried will happen behind the scenes while they have to spend so much time in each other’s company.’

Worrying with good reason. As some have commented, it’s all beginning to feel uncomfortably familiar.

The five had once been very close friends after they met as a group of star-struck wannabes in 2002. They were given flats to live in, at a vast, converted psychiatric hospital in Friern Barnet, North London.

While Sarah, the oldest, and more self-contained member of the group chose to live alone, Cheryl and Nicola paired up and Kimberley and Nadine lived together.

Soon the scruffy, unpolished line-up were transformed into glamorous popstars and went on to sell more than 4.3million singles, 4million albums in the UK alone, and became one of the UK’s most successful girl groups of the 21st Century.

Cracks soon started to appear, however, after Cheryl married footballer Ashley Cole in 2006, launching them into the fame stratosphere, as the next ‘Posh and Becks’.

The marriage, did not last, however. In 2008, Cheryl was left distraught after a tabloid newspaper revealed how Ashley had spent the night with hairdresser Amy Walton. Tellingly, it was Nicola and Kimberley to whom Cheryl turned for comfort.

Later, Nadine’s absence was noted as Nicola and Kimberley accompanied a heartbroken Cheryl on holiday to Thailand as she struggled to come to terms with her husband’s infidelity.

I recall a night way back in 2007 when the band partied at the K West hotel in West London after taking part in Children In Need at the BBC studios which were then held nearby in White City.

While Cheryl, Kimberley, Nicola, and Sarah were giggling together, Nadine was sitting away from them, with a friend. I learned afterwards that there had been a fall-out the day before.

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The five were once very close friends after they met as a group of star-struck wannabes in 2002

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A string of gigs this year will mark 21 years since the group was founded on ITV reality show, Popstars: The Rivals

Meanwhile Nadine was spending more and more time in Los Angeles where she and her family bought a pub. She went on to date Desperate Housewives actor Jesse Metcalfe, who later suffered issues which saw him check himself into rehab.

In 2010 it was revealed that the band were to go on a ‘hiatus’ with one factor behind it being Cheryl’s solo work. She had become a judge on the X Factor alongside Simon Cowell, as well as undertaking a brief stint on the US version of the show.

A tour followed which, say those behind the scenes, was ‘tricky’. I’m told Sarah was her own entity, with her own manager, while Nadine distanced herself from the others, too.

‘It was all very uncomfortable when the mics were turned off,’ says a band insider.

‘The real issue was between Cheryl and Nadine. Sometimes things got really difficult, really vicious. It was awful to watch, and quite sad when you look back at it now.’

The last ‘tit for tat’ row between Nadine and Cheryl happened in 2013, after the band officially broke up.

A furious Nadine hit out at her bandmates claiming she was told just minutes before going on stage for the final night of their greatest hits tour that the rest of the group wanted to split.

She ranted: ‘I didn’t want the band to end, it was as simple as that. I didn’t think we were going to end. We had done all the promo saying we were all together, having a great tour, wearing Victoria’s Secret wings and stomping up and down the catwalk every night, loving every single minute of it. And then, on the very last night of the tour, our management and publicist came up to me and said the girls wanted to split up the band. I was thinking, ‘What?!’

‘I was in hair and make-up, about to get into my costume, and the show was starting in 20 minutes. I was shocked.

‘I went back to my make-up lady and told her, and was like, ‘F***! I don’t have a job! What am I going to do?’ I screamed and cried on stage and off stage.’

Cheryl responded spectacularly, accusing Nadine of being ‘full of s***’ and accused her of holding the band to ‘ransom’.

‘She was the one who wanted to make a solo record. She wants to come out and say we broke the band up? No! She shouldn’t tell porkie pies.

‘OK, so do you want us to tell the truth? She wasn’t going to make another Girls Aloud record until she got a solo deal. I feel she held us to ransom and then made her solo record deal.’

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Three years ago, it took a tragedy to bring the band back together, when Sarah Harding, aged just 39, announced she had terminal cancer

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Cheryl was deemed the only member of Girls Aloud likely to forge a successful solo career, despite the fact that Nadine was widely accepted as the most talented, musically

The row, silly as it seems today, was said to have centred around the fact that Cheryl was rapidly eclipsing everyone, fame-wise.

She was deemed the only member of Girls Aloud likely to forge a successful solo career, despite the fact that Nadine was widely accepted as the most talented, musically.

‘Cheryl herself will admit she didn’t have the best voice of the group,’ says a friend of the band. ‘That, to be fair, was always Nadine and everyone knew that, so she thought that she could go off and have a big career on her own.

‘But as Cheryl’s relationship with Ashley basically made them the new Posh and Becks, she was the star and that made her far more marketable to music labels, so she emerged as the only one who was going to really make it work.

‘That led to ill feeling and things became very tricky. You add that to five women being together 24/7 and you can imagine the rows.’

But three years ago, it took a tragedy to bring them back together, when Sarah, aged just 39, announced she had terminal cancer.

The news ‘hit all the other girls like a train’ says a friend of the band, and they came together for her final months.

‘Sarah’s news came from nowhere,’ says the friend. ‘It devastated them, they were absolutely distraught and felt helpless.

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As the girls reach the final preparations for their tour, everyone involved is praying they can keep past resentments where they belong – in the past

‘Cheryl in particular was in bits. It all seemed so unfair but they all came together to remember the good times with her. All of a sudden the rows and fall outs seemed so silly.’

And in a sure sign that things really were in the past, last year Cheryl, Nicola, Kimberley and Nadine went to see Sarah’s mother, Maria Hardman, to discuss putting together a tour in her daughter’s honour.

Now, as the girls reach the final preparations for their tour, everyone involved is praying they can keep past resentments where they belong – in the past.

As one said: ‘We really hope that however bad frictions get, they remember this is all about Sarah.’