James Mercer has had several identities over the years, but to call his latest endeavour a "side project" would be doing both him and it a disservice. As frontman, songwriter and sole remaining founder member of the The Shins (one of the finest indie-rock bands ever to roam the planet), Mercer's talent for writing literate, intelligent pop songs has been rightly lauded. When he teamed up with producer Brian Burton, aka Danger Mouse, to form Broken Bells, it wasn't so much a meeting of minds as an explosion of ingenuity. Side project? Ha!

Although Mercer and Burton have been acquaintances since 2004, it wasn’t until several years after their first meeting that the possibility of a collaboration was mooted.

"After [the 2007 Shins album] Wincing the Night Away and all the touring, I really felt like I needed a break from The Shins," explains Mercer. "I wanted to stay creative, but do something different. I'd been talking to my manager about that part of it, and then I spoke to Brian about it – and Brian was also in a similar space, and wanted something new and different, and he had the idea of us forming a band . . . Well, that's not quite true; we didn't even know if we were going to form a band, or just do a record. He was very casual about it, but I had never really done anything like that; I hadn't collaborated, writing-wise, in a long, long time. I hadn't ever really worked with a producer in a full producer role, either, so I was kind of nervous. But we scheduled some time, and I went down to LA, and it really took off right away. Within a half-hour, we had the sketch of a song up on the board, and we were on our way."

The pair’s self-titled debut proved a huge hit in 2010, even bagging a Grammy nomination for Best Alternative Music Album. After its success, and the fact that there were ideas left over from the initial sessions, Mercer says that it was a no-brainer to do a second album.

Like its predecessor, their new album, After the Disco, is the result of the two musicians working together in person at Burton's Los Angeles studio; there were no song scraps or ideas being passed back and forth via email, or anything like it. Although it was recorded piecemeal over the course of 18 months, with sessions snatched whenever Mercer took time off from touring with The Shins, that method of writing entire songs together in the same room makes for an undeniably cohesive album. With Burton largely looking after the beats and production and Mercer on melody and lyrics duty, the writing process was a fluid one.

“We spent a lot of time together, yeah,” he says. “I’d fly down to LA, and Brian’s got a spare room, so I’d live in his house. We’d get up in the morning and go have coffee and breakfast, and then off to the studio. We’d spend the whole day together – the whole week, even – so those conversations ended up working their way into the lyrics. And it’s usually stuff that Brian’s going through, because he’s a single guy,” he adds, chuckling. “He had a lot of lyrical ideas on this album.”

Compared to the Broken Bells debut, After the Disco has a certain, well, disco groove that is best heard on songs such as the title track, which sounds like something Shalamar might have done in the 1980s. There is a definite Bee Gees vibe to Holding on for Life, on which Mercer sings a falsetto to funky effect.

“The Bee Gees thing sort of happened by accident, but we were really pleased when we heard it back, because both of us love the Bee Gees,” says Mercer, laughing. “There was the idea of ’80s r’n’b stuff – not so much that we were sitting, listening to specific records – but more about the instrumentation of the music of the ’80s.

“Brian has this huge collection of synthesisers, so we started looking into sounds that were nostalgic to us, to our childhood. Putting together a beat was usually Brian’s job, and I’d start trying to come up with a melody; and I think when you heard those textures, those synthesizers of the ‘80s, I don’t know what it is but for me it caused my melodies to harken back a little bit, as well.”

Mercer is hugely complimentary about Burton's influence on the album, but there is no doubt that he brings his own inward- looking style to the record, too – particularly on stripped-back numbers Leave it Alone and Lazy Wonderland, which lend an equilibrium to the album's overall pace. The freedom of working with someone like Burton, he says, made him think differently about the music- making process in general. After the first Broken Bells album, Mercer says, he "understood the role of producer" and brought Greg Kurstin on board to produce the last Shins album, Port of Morrow, released in 2012.

Burton has been kept busy with eclectic projects over the years, from his partnership with Cee Lo Green in Gnarls Barkley to producing The Black Keys, Beck, Norah Jones and, more recently, U2, but aside from a couple of diversions into the world of film (including a role in Matt McCormick's film Some Days are Better Than Others in 2010), Mercer has spent most of the past two decades in The Shins.

A recent burst of creativity led to him back to the studio with his bandmates in December for a soundtrack project that led to a “really cool song on the side”, but he says that there won’t be a full-length album this year. He is, as he puts it himself, both too busy and having too much fun as a Broken Bell at the moment.

“I think one year into working on The Shins, I probably wouldn’t have been looking for some other option, so I think my perspective has changed, yeah,” he says. “I look back at the stuff that I did early on with The Shins, and there are striking differences, or things that I wouldn’t do now, I guess. So I think I’ve developed as a writer over time. And I learned a lot from Brian.”

That may be so, but what does he reckon he taught Burton in return?

“Hmmmm . . . I dunno; certain chords on the guitar at some point, maybe?” he says, with a diffident chuckle. “But right off the bat working with Brian, I pretty much felt that I could reinvent myself; I wasn’t imagining an audience who were out there, waiting for anything. I didn’t realise how much of an effect that would have, both psychologically and creatively. I felt like I could do anything, knowing that, as producer, he was in the control room and he’d be giving me feedback, and that was so cool. It was really awesome to be able to just jump around and try any crazy idea that I had without having to worry too much about it. It was fun. We had a lot of fun.”

yyy After the Disco is out today