There's almost too many interesting things about Field Music to introduce them with. You could point out that they're brothers - David and Peter Brewis - who get on a lot better than famous sibling pairings of rock music past (the Wilson family and Ray/Dave Davies spring to mind). Maybe the lead should be their proud Sunderland heritage, and the fact that they used to share a rehearsal space with the Futureheads (Peter even used to be their drummer). How about the fact that in 2007, they announced their split - following their second album - only to reconvene two years later, after getting two (excellent) solo albums out of their systems? Then there's their recent claim that they only make about £5,000 a year each from making music - which is their full time job.

These past few months have added further headlines to the Field Music story: the recent limited edition release Field Music Play..., sees them cover the likes of The Beatles and John Cale; a collaboration with Warm Digits just came out on a similarly coveted 10"; and they were nominated for the Mercury Music Prize.

Plumb, the duo's fourth album proper, is another left turn - following two LPs of angular post-punk and the sprawling, two-disc Field Music (Measure), which took in sound collages and found sounds - this time into concise, if no less fractious and exciting (or exceedingly English) Brian Eno-tinged pop music. "I just think it's important for artists not to repeat themselves and keep exploring," David, the younger of the Brewises, explains. "Bands tend to repeat themselves because there's commercial pressure on them to do so - that's generally not a recipe for exciting, original music."

On the Mercury shortlist, the record rubs shoulders with everyone from Plan B to Jessie Ware to Michael Kiwanuka. "It's pretty varied company," David understates. It's unlikely any level of new-found fame is going to change how the brothers operate, though: "I can't say there's much music on the list which is up my street, and outside of Django Django and Roller Trio there isn't really anyone there who operates in the same universe we do. I don't necessarily mean that in a musical way - more that there aren't many artists on the list who would man their own merch stall or drive their own van."

Much is made of how Field Music have actively "avoided" the music industry - represented by their staying put in the North East, rather than moving down South - until now. Sitting just outside of the mainstream gives the brothers Brewis a, well, outsider's view on things. On Plumb this is most evident through some overly political lyrics, in songs with titles like 'Choosing Sides' ("I want a different idea of what better can be") and 'Who'll Pay The Bills?'. "Disappointing but understandable," is how David describes the current level of political engagement from his fellow Britons. "Political expediency has led politicians (and musicians) to avoid telling harsher truths for fear of them being aggressively spun by reactionary tabloids and instead end up saying next to nothing at all. It's no wonder people feel turned off. Unfortunately, that leaves more space in the ballot box and in the papers for the loudest, most-reactionary voices and common-sense in political debate goes out of the window." He adds, "Thankfully, it doesn't appear to be as bad here as it is in the US."

Away from the current state we're in, the the music of Plumb was influenced by looking back. "Different artists and different records have an impact in different ways," says David, "With Syd Barrett, it's about embracing a particular atmosphere and an irreverent attitude to musical rules. When I listen to Leonard Cohen, I want to write more succinct poetry. Roxy Music and the Pet Shop Boys both make records which slot together in a conceptual way without being 'concept' albums in a dawdling, contrived narrative way. We steal from everywhere in every way." Other than that, they're influenced by "the usual" - according to the younger Brewis - "Books, television documentaries, novels, newspapers, art galleries, sociology textbooks."

The brothers look to each other, too. "We've grown up listening to lots of the same music and playing music together, plus, Peter kind-of taught me how to play drums and most of the music theory I know came second-hand from Pete so it's inevitable we'd share a certain take on things," David explains. "We definitely don't agree on everything and our tastes overlap rather than matching exactly but I'd like to think our rivalry is generally of the positive, spurring-each-other-on-to-new-heights variety."

Between 2007 and 2009 Peter and David released solo albums - under the names The Week That Was and School of Language, respectively - which allowed them to come back to Field Music with a clear head. "I think we reaped the benefits of making music for the right reasons," says Brewis, "As soon as we start to feel uninspired or cynical we can just clear the decks and do something else and not keep churning out records in order to maintain a brand or because it's our job. It's insane as a short-term commercial strategy but it's totally essential for our mental health and I think the people who've embraced us and our music probably appreciate our bloody-minded adherence to those principles."

That self-awareness is part of Field Music's appeal - both as people and as musicians. They're pragmatic, smart, and under no illusions as to their place in the current music scene. For example: "Tramlines was a funny one," says David of Sheffield's annual free festival, where the band played the main stage last year, "We're not much of a crowd-pleasing festival band - it's all a bit intricate and subtle - and those folks who are really into it are bound to be outnumbered by folks who want to get pissed and have a sing-a-long. It was especially stark at Tramlines because we went on straight after Frankie and the Heartstrings and if there was ever a band to get pissed and sing along to, the Heartstrings are it."

They may not be optimistic of winning over the drunken masses with the Mercury nomination; "We're doing our best to tone down our usual scepticism and embrace all of the positive aspects of it. It is, after all, the award which the 17-year-old me would have paid attention to," David adds diplomatically - the next step for Field Music is certain: "We've got no plans to do another Field Music record in the near future but right now, when we're feeling a bit tired and worn out, our plan is to make no plans at all." Given everything, you can't really fault them for that.