TRNSMT is expanding for 2018. Over two consecutive weekends, Glasgow Green will make room for headliners Stereophonics, Liam Gallagher, Arctic Monkeys, Queen + Adam Lambert and The Killers. Much like last year, it's an indie-heavy lineup featuring the likes of Courteeners, Interpol, Blossoms, Chvrches and Franz Ferdinand, with a smattering of pop (Jessie J / Sigrid), hip hop (J Hus / Krept x Konan) and full-on rock (the Darkness / the Temperance Movement).

'I can't think of many people who aren't fans of Oasis,' states Wolf Alice bass player Theo Ellis. 'Liam Gallagher's a right laugh in' 'e? You can't really knock him.' Which is lucky as Wolf Alice are on warm-up duties for the Britrock icon and motormouth quote machine. Over two albums, Wolf Alice have proved they are one of the most exciting young bands in the UK, grounded in indie rock but taking trips to the outer limits of grunge via side-steps into heart-breaking folk. 2015's debut album, My Love is Cool, was powered by the fuzzy 'Giant Peach', the punk punch of 'You're a Germ' and the blissful melancholy of 'Swallowtail'.

'We're still exploring music that can be made via our four instruments and what we have at our disposal in the studio,' explains Ellis. 'I think it says a lot about the modern generation that our attention spans are a lot shorter. Stylistically and genre-wise I don't think people have as many boundaries as they used to: they listen to a much broader spectrum of music. Our output is less tribalistic, it's not shocking to love punk music and rap at the same time.'

2017's Visions of a Life was similarly eclectic but offered even more depth. 'I think you can hear a distinct maturity in the musical competency,' adds Ellis. 'It's an introspective record, exploring more emotional sentiments. I feel like it's more refined. As we've got older we've got better. Obviously I'm proud of the first record but I'm also proud of how much you can hear the development of musicianship on the second one.'

This is just the latest stage in Wolf Alice's evolution. They started as a two-piece centred around vocalist / guitarist Ellie Rowsell and guitarist Joff Oddie, with bassist Ellis and drummer Joel Amey joining as the band's style became harder, heavier and more distinct. 'Our ideas were quite ambitious and what we wanted to achieve as a band was quite ambitious. We always had belief in ourselves even when we were awful,' laughs Ellis.

That self-belief was justified and has been echoed in their rapid ascension to indie rock's top table. For a band just years into their career, Wolf Alice have achieved a lot: Grammy, Brit and Mercury Music Prize nominations, playing all around the world (they recently supported Queens of the Stone Age in the US), and even taking a starring role in Michael Winterbottom's On the Road, a film which blurs fact and fiction with Wolf Alice's tour the backdrop to a scripted love story (starring Leah Harvey and James McArdle). 'That concept really appealed to us but when we saw it back the narrative was a little less heavy and it was more of a tour documentary. Which is fine but it explored the mundanity of touring which is a thing you don't necessarily want to promote as a band.'

Touring has become more important, if very time-consuming, for modern bands. It's all about striking the right balance between the visceral thrill of playing to thousands of hyped-up fans every night and the more introspective creative side. 'It goes in waves,' Ellis admits. 'After a while you want to get back in the studio making music. I like them both in equal measure but I don't like anything when I do it for too long. I have a very short attention span.'

Over the last year in particular the public has been more vocal in calling for greater diversity and representation on festival bills. Looking over the posters for the biggest festivals in the UK proves there's still a long way to go. 'I think equal representation in all work places and environments is important,' agrees Ellis. 'If you want young girls picking up instruments and playing music on those stages you need to be able to see other inspiring females. I've seen people come up to Ellie and talk about picking up a guitar or writing a song because of her. So I think of her as a very inspirational person because there just aren't many women doing it.'

TRNSMT Festival, Glasgow Green, Fri 29 Jun–Sun 1 Jul, Fri 6, Sun 8 Jul; Wolf Alice play on Sat 30 Jun.