Girl groups were a ubiquitous part of 90s pop culture. But while the Spice Girls were held up as the new face of 'girl power', with their mainstream-friendly brand of feminism resonating with many, their effortlessly cool counterparts All Saints were advocating for an entirely distinct version of female empowerment. Shaznay Lewis, Mel Blatt and sisters Nicole and Natalie Appleton didn't fit neatly into the shiny pop mould created by the music industry, instead choosing to remain fiercely independent and choosing to focus on the strength of their music over pop consumerism. Having now been in the game for 20 years, the quartet can recognise and truly value their individualism all those years ago.

'Whatever was going on commercially, within our music, I think we always worked with people that were a bit more left of field,' Shaznay Lewis explains. 'From our first album, where we worked with people like Nellee Hooper, Cameron McVey and K-Gee, who himself was originally a hip hop artist, to the second album, which had William Orbit. I think that the way that those producers worked was obviously very different to a lot of the music of that time.'

Although they only made two albums before taking a break in 2001, All Saints' contributions to the pop canon are undeniable, with hits like 'Never Ever', 'Pure Shores' and 'Black Coffee' continuing to inspire a new era of progressive and interesting pop music.

'I think 20 years ago, it was a lot more poppy,' Shaznay says when asked about today's pop landscape. 'I think now, what is mainstream and in the pop charts is a lot more mixed or urban than it was then. If you think back to then, we had a lot of pop bands like Aqua or Steps, and pop was really pop. Which is why we always thought we didn't necessarily fit into the same box because we weren't as typically pop as the others. Whereas now, there's hardly any of that kind of music around. It's a lot more diverse and the pop charts in general are a lot more diverse.'

For Mel Blatt, things have evidently changed but certain challenges remain the same, especially for young women in the music industry.

'I would think that fundamentally, things like feminism and sexism remain at the core,' she says. 'But I think there are different things that maybe are being addressed these days. There's definitely more discussion being had about [sexism] and no one is as ignorant about it now, but it doesn't mean it hasn't stopped or it doesn't happen. We were just having a discussion about mums and dads, and we're always asked what's it like going on tour without the kids. And men never get asked that. It shouldn't really be like that. But as far as women in music, I think we all face different trials but within the same structure. The rules are different but the game's the same.'

With five number one hits to their name since their 1997 self-titled debut, the group recently returned with their fifth studio album Testament, which follows 2016's reunion record Red Flag. The album sees them team up once again with producer William Orbit and long-time collaborator Karl 'K-Gee' Gordon and although there are subtle hints to classic All Saints numbers, Testament takes them to new territory, providing a revitalisation of sorts to their dreamy, harmony-filled R&B.

'Shaz had been in touch with William over the years since we worked with him last,' Nicole Appleton says about their reunion. 'But one night, Shaz and I were out having a couple of cocktails and we bumped into him in the bar. And it was just like no time had passed and we just started reminiscing about a lot of the stuff we had done and being back in the studio, it was just such a natural conversation. So a few months later, there we are back in the studio with him again. It was just amazing.'

As the co-writer of all the songs on Testament, Shaznay's progression as a songwriter is apparent as each track ebbs and flows with varying motifs and harmonious choruses that slot perfectly into the group's tendency for edgier and darker sounds.

'Because we worked with more than one producer, one of the main things I wanted was for it to be an album that was cohesive,' she says. 'In the past, I kind of felt that musically, things didn't always gel because we were working with different producers. So since coming back and doing all of this, that's been one of my main goals really, just to make sure that the music works well together.'

Diehard All Saints fans won't want to miss their upcoming tour, which involves the group travelling across the UK in November and December. 'It'll be a blast from the past, a blast from the future, with some old stuff and new stuff from Testament.' Natalie says. 'It'll just be a really good time! We want everyone to leave the venue feeling really great.'

While comebacks don't always go well for groups that had their heyday in the 90s, All Saints seem to be getting better with each reincarnation, as Testament shows. But how does it feel for them as a group, 20 years later?

'It's just amazing, it doesn't feel like it's been 20 years!' Nicole exclaims. 'Time has just gone by so quickly and if we were to think 20 years ago that we would be out with an album like Testament, it's just mind blowing. So we're really grateful and appreciative to be here after 20 years.'

Testament is out now. All Saints tour the UK, starting in Cambridge on Thu 29 Nov and finishing up at Newcastle's O2 Academy on Wed 12 Dec.