I'm sat in the cavernous Moon Under Water pub on Manchester's Deansgate. As I wait for the perfectly punctual Gareth Smith – the driving force behind experimental rock collective Stranger Son – it dawns on me that the last time I set foot in the building was in 1980. Back then, I was 10 years old and the pub was a cinema. Back then, I'd been blown away by The Empire Strikes Back, but tonight I'm eager to meet the man at the centre of the creative maelstrom of one of the city's most expansive-sounding bands.

Stranger Son are well known to the Quietus - the band showcased their panoramic soundscapes at the Wire-curated Wire:Drill festival back in March. Birthed in 2005, the group boast a number of previous and current members who have gone on to form bands including GNOD, LoneLady and Monster Island. Stranger Son's recently-released five-track album, Last Days of Butterfly, was recorded in the grand surrounds of Manchester's Victoria Baths and is testimony to Smith's desire to continually push the possibilities for what he describes as a "musical continuum".

I immediately warm to Gareth. He buys me a pint (which always helps) and listens to me prattling on about childhood visits to the cinema (as was). In the face of a music industry crashing down around him, he's proud of Stranger Son's achievements and the success that has been catalysed in other bands. There is also an edge to him which I like a lot - he uses music as a tool to express and release his political frustrations, which makes Stranger Son a heady concoction of passion, anger and creativity.

You were part of the Quietus-assisted, Wire-curated Drill festival back in March. How did that come about?

Gareth Smith: The Quietus gig happened because Julie [Ann Campbell], who is in Stranger Son, had previously supported Wire as LoneLady. She'd also done some side projects with Colin [Newman] from Wire. So that was the connection, and Colin asked us to play Drill.

Stranger Son have been active for several years – how did the band start?

GS: I'd been playing in various bands and had given myself a bit of time off. But I was itching to get back into something and began jamming with Chris [Haslam], who would later form GNOD – that was about eight years ago. My previous band [Thee Virus House] had been really hard work. So Stranger Son was something that was fun and there was a lot of improvising which neither of us had done a great deal of. It has developed immensely from that starting point to where it is today.

How has the Stranger Son sound developed over the last eight years?

GS: At the start, the music was very simple – it was essentially guitars and vocal. We'd write endless amounts of songs in that format, because it was easy for us. Around 2007, when we'd only put out a couple of singles, I took over the reins and began to write more. The songs became flatter but more layered. Now the music has a heavy keyboard element with lots of extended passages and is more about elongated soundscapes.

Has this been a slow evolution or have you stylistically jumped from one sound to another?

GS: It's a natural progression. I've never tried to move too quickly. I'm always wary when a band changes style, or disappears and comes back sounding completely different. I never wanted that, because I've always believed in every aspect of our music. I wanted the progression to feel that it was attached to the previous thing. It's always been a continuum, and I hope that that people can follow it back with some semblance of sense, rather than the music having jumped around. The idea of a continuum has always been very important to me.

The new album was recorded in an empty pool at Victoria Baths. Why did you choose that venue?

GS: On the last album [2011's Luna Marseille], I took a lot of time and effort to try and perfect the sound. It's a great album, in my opinion, in terms of where we were at the time. With this album, I wanted something more immediate. I didn't want to be in a studio trying to insert reverb or tones. I wanted the atmosphere there from the start. We found Victoria Baths, which was perfect as it was tiled, so the noise flew around everywhere. It wasn't a gimmick thing and it certainly wasn't funded in any way. The album was recorded during one afternoon and most tracks were two takes.

Victoria Baths is a famous Manchester landmark – have you ever been swimming there? GS: No, but I did find some footage of Tony Wilson interviewing A Guy Called Gerald there. He played 'Voodoo Ray' while there were people in the pool with big inflatables. You should check it out. That was the clincher for me. I knew, whatever happened, it was going to be an interesting recording.

The other very noticeable change to your music on the new album is the fact that you deliver your vocal in a spoken-word style. Why did you use this approach?

GS: It is a massive contrast to what I was doing on the early stuff. I feel more comfortable and satisfied with the tone of my speaking voice and I've been able to deliver messages more strongly. However, I don't have a singing voice as such – it's hardly Charlotte Church – but it's something like Mark E Smith or John Lydon which is kind of the spoken side of singing.

You say the spoken-style helped to deliver messages. Where do you get your inspiration for the words?

GS: Well, the second track, 'French Playground', has a political agenda to it. I'd had the title for a long while and the music had become more cinematic and reverential. For the lyrics, I read a lot about the history of war, so I based the words as a historical document of the Algerian war. I'd also read a book called The Wretched Of The Earth by Frantz Fanon which is about the psychology of oppression – so that was floating around my mind.

Do you see Stranger Son as a 'political' band?

GS: Not directly, but I think everything I have written has been political to a certain extent. I view myself as a Marxist even if you cannot be a Marxist in a non-Marxist society. I am inspired by many events that unfold around me. The reason why I am interested in warfare is that war is an extension of the capitalist system. War is capitalism in action, and I do feel a massive sense of injustice in the world. I'm from a working class family. I've worked since I was 16. I now work in child protection for Manchester City Council so everything around me seems deeply involved in the political struggle. I have a slightly warped view of society because of my job – I've seen more shit than most people.

Without wanting to sound like a psychoanalyst, is music an outlet for you?

GS: Music is definitely an outlet. I started making music when I was 19 or 20. I was working in a factory and a number of people around me in my life had died and I needed a release valve. It's more than that now; it's not as if something upsets me I need to write a song, but when I don't do make music for a while I do feel very unhappy.

The Manchester music scene is very fertile at present. Do you listen to a lot of new local bands?

GS: I don't tend to look for new music. I tend to listen to more American minimalism like Philip Glass and Steve Reich. I like jazz and am a big fan of Miles Davis, and I will still crank up records by Velvet Underground, The Fall and PiL.

Stranger Son don't seem to play a huge amount of live shows. Aside from the obvious practicalities of juggling day jobs, is there any specific reason for this?

GS: Increasingly, as we have tried to introduce different layers of sound, it has become more important to have a decent sound system, so we began limiting the number of gigs we did. So we tried to find more suitable venues – but the downside is we don't play very often. I prefer that to playing lots of shit gigs. Too many bands play too many bad gigs.

What does the future hold for Stranger Son? Where might the continuum be heading next?

GS: Well, personally, I also have other projects - I've made an album with Paddy from GNOD and Zack who is in Stranger Son. That's very much a spoken word thing. but a completely different type of music. As for Stranger Son, I tend to think the next record might be created via jamming and keeping things natural. If you want your fellow musicians to actually feel what they are doing, they need to be there when it's coming together. That's when something interesting can come out. The current band are all really great players, so we may do a bit of jamming and see what comes of it.

Stranger Son's Last Days Of Butterfly is out now