James Mercer came to a realisation when he sat down to begin writing the fifth Shins album, Heartworms. "I decided, y'know what, I'm just gonna go back and do things the way I f*ckin' like doing 'em."

As the main protagonist and only constant in a band borne out of his 1996 Flake Music project, Mercer is well acquainted with both fleeting success and triumphs on a bigger scale. Perhaps that’s why, at this point of his career, he is happier doing things his own way.

The Oregon-based band's last album, Port of Morrow, proved their most commercially successful yet, largely thanks to its lead single (Simple Song) and the momentum generated by its Grammy-nominated predecessor, Wincing the Night Away. Still, Mercer was left wondering where to go next.

"I think with Port of Morrow, there was a certain part of me that felt like I wanted to get the 'straights' in on it," he says down the phone from a snow-covered Portland. "It wasn't a super-strategic thought. It was just, man, I know I'm writing hooky shit . . . wouldn't it be cool if I could continue doing it without selling out my soul, and still have some sort of success that crosses over a little bit?"

Mercer thought the Port of Morrow track It's Only Life would do just. Only it didn't. "And I think that disappointment with sort of maybe putting out an olive branch to the wider world and saying, hey, I'm a songwriter who's accessible, and it not being received the way I wanted . . . I kind of felt why bother, to be honest."

He laughs. "So I think Heartworms is a bit of a reaction to that. It was a bit of getting back into some sort of rebellious spirit. It's not like a punk record or anything, but there is that sort of sentiment somewhere in there."

Most Underrated

Arguably one of the finest (and certainly one of the most underrated) songwriters of his generation, Mercer (46) began writing Heartworms after releasing the second album by Broken Bells, the electro-pop side project that he fronts alongside producer Brian Burton, aka Danger Mouse. Working with Burton, he says, has had an impact on both his personal and professional life.

“It opens me up to working with other people. It kind of taught me how to work in the studio with guests, and how to collaborate, and how to express what you need from somebody. I was really in a different place socially before I started working with Brian.”

Contrarily, Heartworms saw Mercer working predominantly alone in a production capacity for the first time since 2001's Oh Inverted World.

“I think what I missed was just having the time to sit there alone with the songs,” he says. “That’s where all the little weird, quirky things come from; me just being able to sit there and elaborate on ideas without worrying about anybody being frustrated with my tweaking things.

“I’ve always had people helping me with production, but this time I just wanted to do it straight through on my own. Although I have to say that [bassist] Yuuki Matthews was such a partner on this, and he mixed the record. So there’s still a lot of collaborative aspects to it.”

Having more time to sit and tinker with the material means there are a few surprises amid the classic Shins sound, most notably on the synthy Cherry Hearts.

"It probably sounds very different from lot of the Shins stuff from the past," Mercer says, "but initially its working title was Shinsy – that's how much it reminded me of early Shins stuff. I was messing around with it and I had a couple attempts at recording it, and then I just realised, y'know what, it's just too much like everything else I've done. I just can't get into it; it's boring.

“So I started experimenting with this arpeggiator, this synthesiser; I just basically put the chords in and started programming. And I was having a ton of fun with it, and it started sounding like some sort of ‘hey, we’re all going to the pool!’ summer of ’85 thing,” he laughs. “And then all of sudden, instead of being bored, I was like, hey, this is working!”

Unsettled childhood

Other tracks see Mercer delving into the personal trove that he plundered on Port of Morrow, in which he wrote about his constantly unsettled childhood due to his father being in the military. Mildenhall documents his family's relocation to the English town in Suffolk when he was 15, and subsequently discovering the music that would shape him. The song even references The Jesus and Mary Chain with lines such as "A kid in class passed me a tape/ We saw some bands down at the Corn Exchange".

“You probably aren’t that excited about the thought of living in Suffolk, but to me it was exotic and strange. And it was also kind of a bummer to have to leave New Mexico right when I was getting into skateboarding and all of that. But just like everything when you’re a kid, it turns around; you get absorbed into some new social format.

“And, of course, I fell in love with music then; all the Creation Records bands and in-between scene. It was this cool, weird thing to be brought into, and it was very open for someone like me, who was like a shy kid. Suddenly it wasn’t lame to be insecure; it was kind of an asset.”

Name for You, on the other hand, was inspired by Mercer's concerns about his three young daughters growing up in today's society. "I've noticed more and more this latent but pervasive misogyny in American culture," he says. "I wouldn't be so extreme to say that it's some terrible, terrible issue, but it is still an issue.

“I think that it’s revealed in myself in some strange things; I’ll feel a competitiveness to outdo someone based on their gender. And that comes just from deep cultural things, it’s not something anybody taught me directly or anything. So just all of that has become more apparent to me, and I just hope for a future where it just continues to get better.”

He stops, addressing the blonde-mopped elephant that has wandered into the room. “God, it sure doesn’t seem like it now, but it will get better – it will,” he says, resolutely. “This is not the beginning of the end, it’s not. It’s a fu*king fart in history, is what we’re seeing. That’s my take on it anyway.”

Painful pressure

Last year marked 20 years since the founding of the The Shins, but it doesn’t get any easier with time, he confesses with a laugh.

“The process of making this record in the way that I did, putting all that pressure back on myself – it was kind of painful, honestly. My wife doesn’t look back on this last year as the easiest of times with me.

“I spoke to Janet Weiss while I was working on it, and I was like, God, man, it’s so stressful. You don’t wanna fu*k anything up and you’re just worried that somehow you’re making some stupid mistake you’ll regret, because it’s permanent once it’s done. And she said: ‘It was the same for us in Sleater-Kinney, doing that last record that we did.’ And that made me feel so good, because they’re so goddamn good; it was a relief.

“It might be fun to open it up and be a little bit more collaborative again, but maybe in some different way. But 20 more years?” Mercer chuckles. “Yeah. I could probably do that.”

• Heartworms is out now on Aural Apothecary/Columbia Records