In an ideal world there would be a commemorative plaque above the entrance of Liverpool’s Echo arena. “Here ended Girls Aloud, the last great girl band” it would say. On 20 March 2013 Nadine Coyle – one fifth of the genre-bending, pop-reshaping rabble – was getting ready for the final night of the band’s reunion tour. “I was in hair and makeup,” she explains in a north London restaurant, “going through my nightly ritual.” Rather than taking delivery of a good-luck bouquet, Coyle received some news via the band’s PR and manager – the other girls wanted to call it quits. Not the more fashionable “hiatus”, which they’d already done in 2009, but a proper split. With the band working to majority rule, there was nothing she could do.

“It was shocking. We’d signed a new deal and recorded what was basically another new album.” Confused, she marched into the venue’s green room, ignoring video directors there to record the tour for posterity (a DVD), and confronted recent Celebrity Big Brother winner, and closest ally in the band, Sarah Harding. “I said, ‘Do you want to break up the band as well?’ and she was like, ‘Oh fuck it, I can’t be arsed with it, I fucking hate everybody.’ That last show, all emotion was switched off as far as I was concerned, with any of them.”

No longer Aloud ... Nadine Coyle goes solo. Photograph: Suki Dhanda/The Guide

Further ignominy followed: it had been decided the split announcement would be made that same night. Via a tweet. “A tweet?!” Coyle roars in her thick Derry accent. “I saw the draft and just said, ‘Remove my name from that.’ We’d been saying since the start we were properly back.” In the end the tweet went out as the stage was being dismantled. After an end-of-tour party that lasted until the next morning (“[the band] wasn’t drinking together, but we were in the same room”), Coyle posted her own tweet: “You should know by now I had no part in any of this split business. I couldn’t stop them. I had the best time & want to keep going.” Aside from Harding, she’s not spoken to the rest of the band since.

Fifteen years after they formed via ITV’s Popstars: The Rivals, and four years since the split, Coyle has reunited with Girls Aloud’s unofficial sixth member, Howard Hughes-esque production genius Brian Higgins and his coterie of pop mavericks, AKA Xenomania, for new single Go to Work. Alongside lyricist Miranda Cooper, Higgins masterminded 20 of their UK Top 10 singles, including Biology, Love Machine and Something New, shredding the pop rulebook, spray-painting it neon and then painstakingly suturing it all back together to create a Frankenstein’s monster-pop that made everything else – with its boring verse-chorus-verse structure – look decidedly pedestrian.

“The desire to make very startling, very aggressive pop was just bursting out,” Higgins tells me on the phone. “The pop sound of the day was this Swedish R&B-lite sound which I loathed. I wanted to do something spectacular.” That spectacular streak would include 22 singles and five albums in five years, a workload that inevitably led to the break in 2009. “One of the heads from our label came to a London show [on that year’s Out of Control tour],” Coyle remembers, “and none of the girls were really speaking to each other, and he said, ‘When you have 20,000 people out the front and no one wants to be here, that’s the time to take a break.’”

‘I tend to go with the flow’ ... Nadine Coyle.

Despite accusations in 2014 from Cheryl Cole that the hiatus was caused by Coyle’s search for a solo record deal, she’s adamant she initially just wanted a break. “Cheryl had already got her deal, she was ready to go with her solo stuff. I had nothing set up for myself.”

Even before the reunion was announced at a press conference in late 2012 problems appeared. Despite Xenomania creating all their singles, the band, minus Coyle, had decided their comeback song wasn’t going to be glitter-bomb banger Something New but the limp, non-Xenomania ballad Beautiful ’Cause You Love Me (a No 97 smash when it was eventually released). “I was in Disneyland and I was told that was the song they were going with and so I said I couldn’t do the reunion,” she says. “‘Beautiful ’cause you love me’? We’re beautiful anyway! But then I got a call back saying it was now Something New and I was like, ‘OK, let’s do it.’” For Higgins that initial decision not to continue their mutual legacy still hurts. “It’s very difficult to talk about it in a certain sense – there were a lot of emotions.”

Something New-gate aside, Coyle’s decision-making hasn’t always been so finely tuned. “I tend to go with the flow and that flow can end up in great places or not so great places,” she laughs. It’s a trait that got her involved with supermarket chain Tesco which, in an unprecedented move for a non-heritage act, exclusively released her solo, Xenomania-free album in 2010. “It was a really stressful time,” she says. Despite music becoming more accessible, Tesco didn’t want the album available on iTunes, which would have been fine had the CDs been stocked in all of their shops.

Watch the video for Insatiable.

“They had to do online maps for fans trying to find it! I was like, ‘What do you want me to do, drive a truck around and hand them out to people?’” Without the infrastructure of a major label, Coyle took matters into her own hands, hiring her best friend as her assistant. “She’d just graduated from university so I thought, ‘Great, she can help.’ She was a wreck at the end … I was a wreck at the end.” After all that, the album peaked at No 47.

Shortly afterwards, having already moved to LA while still in the band, she bought and ran a restaurant in Orange County called Nadine’s Irish Mist. Then, in 2011, during a nine-month stint in New York, she recorded a single, Sweetest High, even rebranding as Nadine 2.0. “Did that song really come out?” she asks. “It did, didn’t it? I may have been drunk a lot around that time.”

Other impulsive flights of fancy included a duet with Westlife’s Shane Filan; a stint in professional leg-wiggler Michael Flatley’s Lord of the Dance: Dangerous Games extravaganza; and, in late 2009, some gardening as part of a world record attempt for the most trees planted in one site in an hour (26,422, FYI). Even her decision to return to a pop landscape that has replaced the fizzing pizazz of those Girls Aloud curios with slower tempos and Spotify algorithms was more of a whim at first. “Late 2015, I got into a taxi to meet a friend in Primrose Hill and the radio was playing song after amazing song,” she explains. “I thought, ‘Who do I know that does songs like this?’ So I texted Brian.” However, Higgins, and Xenomania, hadn’t been making amazing songs since 2012, the year they created their last UK Top 10 single for X Factor also-ran Amelia Lily.

Out of control ... Girls Aloud in happier times.

“For five years of [Xenomania’s] 21 years we’ve been in the wilderness, just trying to work out in what way we could be amazing again,” Higgins says. While on paper Coyle’s flighty, Housewives of Derry persona seems at odds with Higgins’s Rain Man focus, there are similarities, the reunion representing a return to her comfort zone. “When I was 13 I’d record myself on my karaoke machine and if I didn’t like it I’d record it again. I’d do that for hours, making sure each line sounded just right.” For Higgins, you sense this is about giving Coyle – “a world-class vocalist” – a proper stab at a solo career.

“Nadine’s going to have her go and that means a lot to me – that there are no regrets,” he says. Ask them both what their expectations are for Go to Work and the answer is similar. “I have none,” Coyle says, which feels like something she shouldn’t say too loudly in the corridors of her new label, Virgin. “I’m measuring success in different ways now,” says Higgins, aware that those chart-dominating Xenomania days are behind him. “It’s a great peace of mind for me what’s happening with Nadine.” Whether Go to Work represents a kind of closure or the start of – wait for it – something new, Coyle’s joy at being back is palpable.

“I’m so excited,” she confirms. “I could cry when I think about how good it’s all been.” The day before our chat a speculative news story emerges suggesting Sarah Harding’s CBB performance has nixed a possible Girls Aloud reunion. “It hasn’t been discussed, no,” she replies, before spotting a magpie out of the window and offering a little salute. “One for sorrow,” she says. Would you ever get back together? “To be truthful, I didn’t want to break up in the first place. So I would have been sitting here with the other four. I was happy to continue.”

Go to Work is out now