Big Mama is a small venue tucked away in a nondescript corner of Rome's Trastevere district. Once the rough and ready by-word for the feisty, lairy Roman working class, it has since become one of the most fashionable, gentrified parts of town, full of bars, American students, and bars full of American students. Here you're somewhat set back from the main action, on a back street off Viale di Trastevere, which bisects the neighbourhood and takes you over the Tiber and into the centre of town. The venue is underground and seats no more than 40 people, although tonight there are plenty stood up in-between the bar at the back and the tables and chairs at the front. The stage is small, enough for retro-pop curio Gemma Ray, her organist and drummer, but not much more, and the tightly packed crowd are warm and appreciative. It's mid-March and today was the 150th anniversary of Italian unification, as well as being a bank holiday, so everyone is in a fine mood.

Ray is in Rome at the start of a three-date practice tour, preparing to play her fourth album live, and the set reflects that; she plays five songs from the forthcoming album, which we were told pre-gig is going to be 'lush-sounding'. Eventually she wants to have a six-piece, but even with the stripped-down backing she has tonight everyone is eating out of the palm of her hand; she casually chucks out faultless renditions of her best songs while looking as though she was doing a backstage warm-up, and by the time she starts playing the first notes of 'So Do I' – the third of an 18–song set – a rapt silence has enveloped the crowd, punctured only by the applause that fills the gaps between songs. While pottering through the set she fiddles with her monitor, complains about death of chivalry in England, remarks on the traffic, retunes her guitar and runs the back end of a kitchen knife down its strings. Post-gig she and her manager set up a small table from which to flog albums, and before we settle down to talk, a long line of appreciative people forms to buy her records and lavish her with compliments.

In person Gemma Ray is more like any number of girls I grew up with than the mysterious pop curio she is usually portrayed as. Her accent is toned-down Essex Estuary English, and she's as bright as her dressing room was dusty: ideas come tumbling down as she speaks, so that often just as she's about to articulate something, another thought pops out which she then hastily tries to corral into her response. She's engaging and passionate and could clearly talk about music all day and night (our 45-minute chat was cut short only by the venue closing).

So you're already writing new songs?

GR: Yeah I think it's quite natural. It's kind of cathartic when you're going through mixing, or even mastering, which I find quite painful. We're mastering the single at the moment and it just feels like a release to be working on something new. This period can be really frustrating, but you can have more spare time to write other stuff.

Do you not feel like you're in a kind of limbo period? Are you conscious of the fact that six/eight/10 months down the line you could be big?

GR: It's not healthy to think about it like that. The key is to keep being creative, and if you think about anything outside that, you're fucked, because everything gets warped, you're not thinking of the music. I certainly don't think about where I'm going to be, and it's not the way I live my life. And also I don't have expectations because I've never been with some cheesy major label and a shit manager, with whom you have meetings and do loads of coke, and talk about how great you're going to be. The main pleasure is the creative process and doing something new – that's an addiction in itself. Obviously I love it when people love my albums and you get positive attention and you get a great response from a crowd. I'm interested in that because it means you're reaching people, and the more people you reach the more experiences you have and the more money you get to record, and you get to hire (Roman-born Ennio) Morricone as your next producer. I'm interested in success - I can't say on my own terms as that sounds so clichéd - but success is only something I can measure by creative output. You know?

Q: What direction are you going in with the new album? From what I can gather there's less genre-miscegenation and a stronger single stylistic thread?

GR: A little bit, in terms of mood. But to be honest I don't have a very big vision. I can only see what's right in front of me, one problem at a time. I'm starting to get enough space that I can see it as a whole album, but I'm still getting used to them all (the songs). I just like to open my guitar case and play my guitar and have a tuning that captures my imagination, so I keep the whole creative process a mystery. I go by instinct and I do the same when I'm doing an album, and work out afterwards how it fits. I'm kind of superstitious with a new album as well, as I don't want to put any kind of firm impression on it until it is fully formed and fully mixed. I just write songs and try and honour that moment when they first come into shape.

You seem really hands on.

GR: Yeah I am, definitely, but I've never known it any differently and I'm really grateful for that. It's been a slow burn and it's allowed me to develop my own style. If I was 18 I think that if I'd have been working with producers I'm sure that something good would have happened, but even at that age I know I wouldn't have done it because it would have freaked me out. Having said that, I have worked with Michael Sheehy who had a lot of input: if someone's talking sense to me then I really wanna learn. It's the same with Andy [Bronzerat] who runs the label [Bronzerat]. We've worked musically together from quite a young age and collaborated with him on artwork. Basically I bounce stuff off him and see if it comes back. I do have complete control but I'm not arrogant enough that I always choose my way: there's a lot of people who I enjoy getting advice from. We share a similar vision so it's not a big problem. I don't have to fight for everything.

Where do your songwriting influences come from? You were into Sonic Youth and grunge at the start: I can see how that influences your music but if someone was to come to it now they wouldn't think 'she loves Sonic Youth'.

GR: Basically I don't feel like I have many influences because I don't listen to music much. The one thing I do feel I have been influenced by is John Barry [Prendergast]. And I realised recently that Tales Of The Unexpected TV series – that was always on at my bedtime, and I know that I had to go to bed when it came on, and I remember being really scared but sitting on the stairs and still listening; and it's only recently that I heard it somewhere and then I realised that pretty much all of my chord progressions and that slippery major/minor thing have come straight from that. I tend to listen to one record a year. I've been listening to John Barry's Remember Me for about five months, every time I have breakfast lunch and dinner, and then that's it.

[At this point The Quietus relays the story of how, when trying to cheat on his GCSE English, his cousin played 'Mo Money, Mo Problems' by Puff Daddy, Mase and the recently deceased Notorious BIG at least fifty times one afternoon, and just how fucking annoying it was.]

GR: I get a bit like that. Like with the snare drum at the start of 'Wouldn't It Be Nice' by the Beach Boys. I had a bit of a problem with that one, and it wasn't on vinyl so it was really easy to just push the button and go (whip cracking sound). I can imagine it being quite annoying; I did it with a particular Gershwin compilation that I had for four years – I couldn't stop listening to that. I love Etta James, and I love the way in that time it was all separate: you were a great singer; or you were a songwriter who wrote 20 songs a day; and then you had all the jazz and soul musicians who were playing those songs. And that's just the covers album.

Q: What's the recording process like when you're on the road, given that you write so much? Is there a system you use?

GR: I used to use my Sony Ericsson, which was really shit and taped together. I don't believe in demoing songs because you always end up chasing the demo, so I started looping up songs on my Loop Station and then recording it really badly on my phone, so you can hardly hear the song; you get the mood and that was the only thing I referred to in the studio. So I drove musicians bandy, like 'it needs to sound like this', and they're like 'I can't hear anything'. If you try and make a demo you're fucked – you never have a moment twice. So you need to create for the first time in the studio. But I've now progressed from that, as my friend Rory [the evening's organist] has bullied me into buying a dictaphone, so now I'm as professional as you are... I do feel like there's a lot of shit indie bands, four boys with brand new Fenders who have thin picks and don't realise that they only sound good on vintage guitars, jangling away in their gap year, before becoming estate agents. That kind of thing where you think: 'Where's the version of that where they've actually got songs and grit and meaning?'

You either make music or you don't, I suppose.

GR: Exactly. And I don't go out much because I'm too busy making music so that side of things doesn't bother me. You know, you do make some choices in life and I'm definitely a better person when I'm doing music.

Does that independence mean you can cocoon yourself off and plough your own path, musically, without any outside influences?

GR: Yeah, and that's why I write a lot, because I allow a lot of space for it. If you don't have space for it then you're not going to fit it in. If your creative drive is strong it will always get through, but it depends on whether you want to write one album every three years or three albums a year. I need to be doing something that I believe in, writing wise. I'm not bothered about propping up the album, I just need to... I just know that I get ill, I get physically ill, if I don't make something and put it out into the world. It's just the way I am. Even as a child I was constantly making stuff, you know? With glue, papier maché; If I don't make something for a week I go weird.

Creating something tangible rather just having ideas and jamming, and actually putting them together and forming them into something.

GR: Definitely. That's a good way of putting it. I like turning my ideas around and expressing them. I like stuff that doesn't answer anything and might not even have an end, but still in a contained format that makes sense to me, and that's popular, whatever it is. If I didn't have that natural fascination to make that, then God knows, you know? [wistful gaze]

That's the thing that unifies everything I do I suppose, putting it all into a digestible format. I'm always much more chuffed if someone says that they've got a girlfriend who's not into music but they liked what I did, or if your aunt and uncle like it... Or getting a good album review in The Sun, which meant a lot to me. I'd rather that than The Guardian. I've got nothing against The Guardian, but it's more of an achievement. If you can do something on your own terms and you get through to people who don't go out looking for it, that's a bigger achievement, the most exciting thing there is.

Pure pop.

GR: Yeah. Pop in the real sense interests me. Like when you talk about Pet Sounds, and especially the girl groups; I love them. You know those weird little one-and-half minute songs that are full of reverb? I love that. Or if you can sneak something in that's really fucked up, whether it's a sound or a lyric or a concept.

It sounds a little bit like problem solving: how do I take all of these concepts and form them into a three-minute block, and make it work?

GR: If a song doesn't come through 'organically' as a whole then it does become a puzzle, and the best kind of puzzle. Nothing stimulates me as much as that puzzle. Some of them pop out fully formed but I do quite enjoy wrangling with the awkward ones as well.

What about themes for the new album?

GR: The new album is a bit more otherworldly; I like the power of words, and I like to evoke a feeling I suppose, a mood. The theme is being in big expansive places, which is pretty broad, but I did record it while travelling around the world. I don't want to jinx it or talk rubbish until it's all clear in my head, but from my perspective it's kind of like a photo album, in a way, of my travels last year. Although obviously not literally. But once I've written a song and recorded it it's out there for the people to decide what it is, and that's how it should be.