Lisa Hannigan is proudly showing me iPhone photos of her new baby. "Isn't this one gorgeous? And look at that, aww! "They're all beautiful," she coos again, "but this is my favourite!"

The name of Lisa's bundle of joy is At Swim. It was given birth to last September in a New York church after what she admits was a difficult gestation, with Aaron Dessner of The National acting as musical midwife. "I haven't got the physical CD or record yet, but my manager, Ben, has just texted me these shots. There's something particularly magical about vinyl. I love the crackle you get when you take it out of the sleeve for the first time!"

Ah, yes, the sweet, sweet sound of static. When Lisa Hannigan released her last album, Passenger, in October 2011 she never dreamt it'd be five years before she'd be making goo-goo eyes at its sibling (that's the mother/child analogies done with, by the way). "I'm not like One Direction having to make an album every 18 months because the record company share price is dependent on it, but I never intended it to take so long," she says putting down her phone. "I toured Passenger for around two-and-a-half-years and during that period wasn't able to write, which hadn't been my experience before. I thought, 'No problem, it'll start flowing as soon as we come off the road'. That didn't happen, though. I tried hard - probably too hard - to write when I got home from the tour, but was only able to come up with fragments and half-ideas."

Lisa was beginning to worry that her songwriting mojo had deserted her for good when the aforementioned Mr. Dessner sent her a "Can I help?" missive "I'd been musical penpals with Aaron for a while," Lisa resumes. "He'd mail me these beautiful pieces of music, which I'd hum along to and record on my phone. I guess I had three or four songs I liked and 20 or so that were hiding under the sofa when he suggested I come over and visit him in Denmark, where he was with his family. We got together in a warehouse space with a computer and bashed out the songs we'd been working on and wrote some new ones."

Those Danish demos were turned into an album when Lisa and her band - Ross Turner on drums and bass and Cormac Curran on piano - decamped to the 19th century church in Hudson, New York that's been converted into the strictly analogue Future-Past studio. The National have recorded there, as have Arcade Fire's Richard Reed Parry, Merchandise, Little May and a host of classical types far too highbrow for the likes of you and me to know. "It's such a beautiful space," Lisa enthuses. "Apart from all the equipment that's been brought in, it still looks exactly like it did when it was a church with the altar painting and the hanging lights and stained glass windows and everything. Hudson itself is in upstate New York, and really rural with chickens and sheep on the sides of the road. Even if we'd been up for mad partying there wasn't anywhere to go!"

It must have been pretty frantic, bashing out an entire album in a week. "No, not all!" she insists. "It's mad, Aaron's a very laidback person and that calm spreads to everyone else. After we got the songs down and I came back here, he took it home and added all the textures whilst at the same time finishing off a 59-track Grateful Dead tribute album!" One of the standouts of the latter being the gorgeous version of 1969's 'Mountains Of The Moon' that Lisa duets on with Sonic Youth co-founder Lee Ranaldo.

With The War On Drugs, Jenny Lewis, Mumford & Sons, Kurt Vile, Bonnie 'Prince' Billy, Stephen Malkmus, J Mascis, BŽla Fleck, Lucius, Courtney Barnett, Sharon Van Etten, Local Natives, Phosphorescent, Perfume Genius, BŽla Fleck, Anohni, The Flaming Lips, Bill Callahan, Sam Amidon, Fucked Up and The National, natch, also pitching in with tracks, Day Of The Dead (Red Hot Compilation) may just be the tribute-iest tribute album ever!

"I don't think there's any Irish or British equivalent of the Dead - they're such a cultural touchstone for American musicians," Lisa reflects. "I'd seen them in the Festival Express documentary, but because I was watching it for Janis (Joplin) I didn't realise how influential they are. It ended up being ten records, so the scale of that project was astronomical. What I've really been struck by, in my time working with Aaron, is how hard-working and generous of spirit and creativity he is. He's so open to the possibilities of collaboration, and gives without thinking what he might get in return."

Lisa got to see Dessner doing his day-job last month when she joined The National on stage at Longitude for a rendition of 'Fake Empire' that put goosepimples on your goosepimples. "We are having a fucking blast," drawled Matt Berninger (as he does) before inviting out "one of our favourite singers... oh man!" "God, yeah, it was an absolute thrill," Lisa beams. "Aaron said, 'Any chance you're in Dublin and want to come sing with us?' and I elbowed my way straight there! They're incredibly focused on what it is that's at the core of their music and refuse to dilute it. They were expecting an older crowd at Marlay Park, and were genuinely blown-away when they saw 16-year-olds singing along to their songs."

Was Matt's errant, documentary-making brother Tom there? "No, and I was really hoping he would be, because I love Mistaken For Strangers; there's such an amazing, warm heart to the whole thing. I have a feeling we'd get on, but Tom wasn't part of the set-up this time." The 35-year-old will be hooking up again with Aaron this month at Eaux Claires, the rural Wisconsin festival he co-founded last year with local resident Justin Vernon. "It's almost a fantasy festival line-up with Beach House, Mavis Staples, Erykah Badu, Nathaniel Rateliff, James Blake, Jenny Lewis and Bon Iver all playing beside a lake," Lisa beams again. "I love being able to just pack my bag, jump on a plane and do wonderful things like that."

Asked whether any musical differences arose whilst they were making At Swim, Lisa replies: "I think Aaron would have liked a few more guitar solos, but whenever he'd suggest it I'd say, "Hmm, maybe we should have a violin instead!" While violins are in short supply, Lisa does get to perform her very first banjo solo on At Swim standout, 'Undertow'. Its creator sounds blissfully loved-up as she intones: "I want to swim in your current/ Carry me out, up and away/ I want to float on every word you say." The inevitable "Is he real or imaginary?" question results in an enigmatic smile and the non-committal: "That's for you and everyone else listening to decide. Obviously it's a very rich well of inspiration in terms of writing, but I feel like it's less romantically tilted than my other records."

Make of that what we will? "Yes!" Amidst all this admiration for Aaron Dessner, it oughtn't to be forgotten that Lisa is also an accomplished multi-tasker. A case in instance being the Soundings podcast and series of live events that she's been putting together since 2013 with Dylan Haskins. "He moved over to London, where I was based at the time, and said, 'Here, shall we do something?' That 'something' turned out to be this cultural podcast where we interview people with stories and songs. Actually, Dylan does the interviews while I sit there desperately clutching my one question!"

I hope this has given her newfound respect for us journalists. "Absolutely! I didn't realise how tricky it is to have a conversation with someone rather than it being, 'Here are ten questions I'm going to ask you!' I was very Alan Partridge-esque at the start, but think I've got a bit better since. It helps when you have smart, talented people like Sharon Horgan as your guest. We've a few mutual friends, so it was nice to catch up.
Catastrophe is the funniest thing I've ever seen; so real and viciously resonant. Another dream interviewee was Giles Duley, the war photographer. He lost three limbs in Afghanistan from stepping on a landmine, but still has this incredible lust for life. He's just back from Syria, so there really is no stopping him."

Lisa almost lost her professional cool when she got to meet Derek Smalls, AKA Harry Shearer, and sing 'Silent Night' with him and the missus, Judith Owen. "How could you not flap being in close proximity to Derek Smalls and his cucumber?" she deadpans. "He was absolutely lovely, though."

Hannigan also got to grace the latest season of Fargo with a version of 'Danny Boy' quite unlike any you've heard before. "The writer/director, Noel Hawley, got in touch to ask whether I'd do a dark, disturbing 'Danny Boy', which is a dream brief for an Irish person," she recalls. "So myself and Cormac Curran went to a studio with a very broken and unyielding harmonium and did a simple, strange version of it with odd, dissonant drones and it worked really well. I think it was the greatest show I saw last year; top to bottom, it's so well realised."

Is she a regular TV binger? "Not as much as I used to be because I've started an Open University English Literature degree. When everyone else is glued to Game Of Thrones, I have my nose stuck in some highfalutin book. Well, not always... there has to be time for Game Of Thrones in everyone's lives!"

When asked for her recommended summer beach reads, Lisa shoots back: "Anything by Paul Murray 'my favourite writer. I asked him to do the bio for At Swim and happily he said 'yes'. I also love Colum McCann."Hannigan got to make her voice-acting debut as a mermaid in 2014's Song Of The Sea, the Oscar-nominated Irish animation that also featured seasoned thesps Brendan Gleeson, Fionnula Flanagan, Pat Shortt and David Rawle. "I'm still not 100% sure why I got the call. It might have been because K’la, who are friends of mine, did the music for the film. Anyway, they approached me and asked, 'Would you be up for this role which is mostly singing with a little bit of talking?' and I tentatively said, 'Yes' - because it's not something that I'd done before. They were so kind and helpful and understanding of my nerves. I wasn't made to record with Brendan Gleeson, thanks be to God! Derek Smalls was bad enough but I'd have passed out if he'd been there while I was attempting to act. Like being an interviewer, you don't know how hard it is until you try it yourself. "You're there for an afternoon and it's done. Then you sit down months later and watch this incredible thing unfold. It's the most stunning, heartwarming, deep and meaningful movie I've seen in such a long time."

Did Lisa get to put her posh frock on and walk the red carpet? "I don't have any posh frocks, but I did walk the red carpet in my non-posh frock and had a fun time." Whilst proud of her involvement, Hannigan regards Song Of The Sea as very much a one-off. "I loved the animated stuff, but proper acting isn't really something I'd want to get into. The thing about the film industry, which is slightly alarming, is that you have a succession of people passing batons to each other. You're involved but not even the slightest bit in control. I love the fact that with music you're steering the whole creative process from the songs themselves to the artwork and the videos."

Another person who helped Hannigan overcome her writer's block was her Devonian pal John Smith who, fact fans, is currently recording a Christmas album with Cara Dillon. "It's a very different experience writing a song with no autobiographical nugget to base it on," she proffers. "You have to find some sort of common ground, which isn't always easy. I liked the problem-solving aspect - 'Well, what rhymes with that word? We need a key change!' - that I couldn't quite apply at the time to my own songs. We wrote 'Coming Home' with Gabrielle Aplin, which was a lot of fun - but there were other projects that fell through."

Lisa Hannigan was among the millions of people who got up on Monday January 10 and immediately wanted to go back to bed when they heard that David Bowie had died. "It was so shocking; it felt like he should always be there," she rues. "I remember as a kid prancing around the living-room to 'Let's Dance'. I've taken a bit of solace from the fact that he was still alive when the reviews saying Blackstar was his best record for 20 years came out. It was such an artistic high to end on."

"Someone said on Twitter that, 'David Bowie was holding the fabric of the universe together', which I'm starting to think might just be true with all the awful stuff that's been going on in the Middle East and Europe. There are days when I have to force myself to watch the news because it's so upsetting.' There's a whole book devoted to the impact that Bowie and the Spiders blasting out 'Starman' had on Top Of The Pops viewers in 1972."

What was Lisa's first rock 'n' roll Damascus moment? "I remember hearing Kristin Hersh's 'Your Ghost' on the radio when I was 16 and being overcome with emotion. Up till then, believe it or not, I'd been the bedroom Maria Callas and only listened to opera music: obsessively so! I'd learned a bit of classical guitar when I was younger and started picking out Joni Mitchell and Paul Simon songs. I still know every single word of Graceland from start to finish."

Little did Lisa realise as she strummed along to 'You Can Call Me Al' in her bedroom that she'd get to perform with Simon at a Seamus Heaney tribute night in the National Concert Hall. "I'd written the music to one of his poems, 'Anahorish', which has subsequently ended up on At Swim, and they asked me to come and sing 'Sliabh Gallion Braes', which is his wife Marie's party-piece. The thought of doing it on my own was too nerve-wracking, so I asked Zoe Conway and her husband John to accompany me. We arrived and the dressing-room a few doors down from ours had a sign on it saying 'Paul Simon', which struck the fear of God and the excitement of all the Christmases of the '80s into me! The show had just started when we heard a little knock on our door. I opened it and, lo and behold, Paul Simon was standing there. He'd heard us rehearsing earlier on and wanted his own private performance. So there we were in a room the size of this table singing to my childhood hero. It was simultaneously the most wonderful and most terrifying moment of my life!"

The only other musician who's made her go all weak at the knees like that being pioneering jazzman Herbie Hancock. "Who's as kind, generous and passionate as Paul is," she notes. "At first it was me and Damien (Rice) doing 'Don't Explain' with him on a record, and then I sang a Bob Dylan song, 'The Times They Are A Changin' with The Chieftains for his The Imagine Projectalbum. We've done a few concerts together including his 70th birthday party in the Hollywood Bowl. That was fun!"

While Lisa's songs deal with the personal rather than the political, she was a vocal supporter of last year's Same-Sex Marriage "Yes" campaign and this week took to Twitter to bemoan the taking down of Maser's Repeal The 8th mural in Temple Bar. "I was part of the 'home to vote' gang," she says. "It was a proud, incredible moment in Irish history that I think we'll treasure forever. There are a lot more battles to go, especially regarding women's reproductive rights. Being of child-bearing age it affects me directly, but I think it affects us all directly. Amnesty International did a very thorough poll in the last few months, which showed that Irish people would by a vast majority like to repeal the 8th and want a change in the laws to make them more reasonable. There's a certain percentage of people who are anti and will always remain so, but the vast majority don't feel that the situation as it stands is acceptable on any level."

Lisa is also concerned about the impact Brexit might have on the North. Would she take a united Ireland over the restoration of a hard border? "Who knows how this omni-shambles is going to work out?" she sighs. "Whether armed or unarmed, I can't imagine that anyone wants a return to checkpoints. As for the broader issue of a united Ireland, I feel like it's up to the people that live there. The most important thing is that we don't go back to the bombings and shootings. The priority has to be peace."

Having not released new material for such a long time, Lisa admits to being nervous as hell when, with no prior warning, the 'Prayer For The Dying' lyric video was posted onto YouTube. "You're sat watching your Twitter feed thinking, 'What if they hate it?' but the reaction was instantly positive. 'Prayer For The Dying' was written quite late in the process. It only took a few minutes and felt very natural. I thought it would be a good introduction to the directness of the record."

A warm, cosy duvet of a song, it finds Lisa channeling her inner Patsy Cline as the boys switch into Nashville twang mode. "One of the Booka Brass Band paid me the greatest compliment I've ever received when we were on tour and I was practicing it. He said, 'Oh, it sounds like 1950s Radiohead!' It's not how I'd describe it, but I put it in my back pocket so when I'm feeling low I can take it out and remember it dearly!

"There's definitely an alchemy to writing," she suggests. "Too much labour is a sign of it not being a great song. That said, Leonard Cohen spent 15 years writing 'Hallelujah', so what do I know?" Apart from the pressure she put on herself, there appears to have been no one screaming 'Where's the effin record?" down the phone at Lisa while she was slowly assembling At Swim.

"No, the people I work with are far politer than that!" she chuckles. "As I said earlier, keeping a whole economy afloat is not a problem I face, which makes it a far easier prospect. I don't know how anyone deals with being responsible for hundreds of people's livelihoods. I remember talking to my tour agent when he came to see us play somewhere in Europe in this lovely little theatre. He looks after Radiohead, so by his standards I'm small-fry, but he said, "This is my favourite level of gig because everyone's having a good time, there's no stress and you're getting to play with your friends'. I thought, 'That's a lovely way to put it'. I've a huge amount of respect for Adele - the way she's handled herself and her career is amazing - but I'd hate the pressures that come with being that successful. As long as I get to make the records I want, tour and jump on a plane to Wisconsin from time to time, I'll be happy!"