8 Jun 2008: Former Belle & Sebastian singer Isobel Campbell tells Amy Raphael about her brilliant new collaboration with gravel-voiced American vocalist Mark Lanegan

Isobel Campbell pulls her beige raincoat tight around her chest, then absently tucks some stray blond hair into a leopardskin hairband. She keeps dropping her week-old iPhone – it’s the first mobile she’s ever owned – and mutters how hard it is to keep it looking shiny and new.

Although she has just turned 32, there’s something both childish and strangely old-fashioned about Campbell. She certainly knows about the latter; it’s not just her love of Sixties pop (Buffalo Springfield, Lee Hazlewood and Nancy Sinatra) or vintage French music (Françoise Hardy, Jacques Brel). Taking tiny sips of water, she says she’s been a grumpy old lady since the age of 21. When she was studying music (more specifically, the cello) at Glasgow University, a friend used to say she was born to be a mad old woman. As she relates this story in her tough but expressive Glaswegian accent, Campbell pulls lots of comedy faces and then laughs; she punctuates almost everything she says with an infectious, throaty roar of laughter.

She probably remains best known as the classically trained musician who spent six years in Belle & Sebastian before walking out in 2002 to do her own thing. Sunday at Devil Dirt, Campbell’s second collaboration with American vocalist Mark Lanegan, formerly of supercool rockers Queens of the Stone Age, received universal critical acclaim upon its release last month (the pair begin a short tour of the album this week). It’s a beautiful, haunted album of gothic blues, better even than its impressive predecessor, Ballad of the Broken Seas, which was shortlisted for the Mercury Prize in 2006. Yet Campbell is a reluctant interviewee.

As soon as we sit down, she talks about how uncomfortable she is in London; I ask if she’s desperate to get back to Glasgow, the city in which she was born and has always lived. ‘Noooo,’ she says, violently. ‘I’ve got to get out of the city. It’s all I can think about. I’ve got to learn to drive so I can leave Glasgow. My friend’s mum lives in this croft that looks over Loch Ness. I was there at New Year, thinking, “I want to do this. Yes, I can do this.”‘

Last year it was America. She didn’t even get as far as deciding where she might live (I thought perhaps the west coast, given the longstanding connection the area has with alternative Scottish musicians – Glasgow bands endlessly namecheck Buffalo Springfield and Kurt Cobain was in love with the Vaselines, who came from the Glasgow suburb of Bellshill). But she’s already moved on and is talking about the Highlands. Her boyfriend, Dave, ‘a builder who speaks fluent Spanish’, lives up there. She races on again, laughing about how they met in December when she’d just finished recording Sunday at Devil Dirt and she was exhausted, broke and convinced she’d never meet another bloke because that’s what she’d been told by an astrologer.

The lyrics on both Ballad of the Broken Seas, the first collaboration with Lanegan, are nearly all written by Campbell and suggest that she has had her heart broken many times. ‘I kind of have,’ she says, dropping her voice to a whisper. ‘I totally have! How can you write about what you haven’t experienced?’

She won’t elaborate; when she talks about all the letters Belle & Sebastian co-founder and frontman Stuart Murdoch used to send to her (‘I’ve kept them all’), I ask if he really loved her. After all, they had what she once called an ‘on-off relationship’ while she was in the band. ‘Only he knows. I suspect….’ Her voice trails off.

Campbell put out four solo albums after leaving Belle & Sebastian, but her first real critical success was with the romantic melancholy of Ballad of the Broken Seas. Mark Lanegan initially appears to be an odd choice; the recovering drug addict has a forbidding presence that makes him seem scarier than Nick Cave and darker than Leonard Cohen. Yet Campbell knew what she was doing and her delicate voice blows in and out of Lanegan’s seductive growl. She wanted a male vocalist with a low voice; she often thinks in cinematic terms and Robert Mitchum in The Night of the Hunter was an inspiration. Her boyfriend at the time suggested she listen to Lanegan; impressed, she sent him a Man Ray postcard, a melody and a single sentence of a song. ‘I didn’t expect to hear anything back but he phoned me up and said he’d written some more lyrics, [adopting ridiculously deep, gravelly voice]: “Do you mind the word ‘baby’? I wish you could be in LA to sing with me now.”‘

She knew nothing about Lanegan’s reputation but was ‘a bit dubious’ before meeting him for the first time. ‘He was in Glasgow with Queens of the Stone Age in around May 2003. I don’t go out much – I never have – so it was quite a new thing to be at this rock concert with all these kids going mad. I felt like a scientist observing some event. I got quite tired in the middle and had to go to the toilet for a sit down.’

Although Lanegan’s stage persona is of the stand-still-and-say-nothing variety, Campbell was charmed by him. ‘Mark’s battled with drugs for at least the last 20 years but we get on great and, off stage, he rambles as much as I do.’

Campbell left Belle & Sebastian because she craved creative freedom. She says she was having lots of ‘Judy Garland moments’ where she’d sit in hotel rooms and feel like the loneliest person in the world. I ask if she felt like the girl in the band without a voice and she says ‘kind of’.

Despite having complete creative control, little has changed. ‘Mark and I played Newcastle, and afterwards this guy came backstage. He went up to Mark and said, “Yeah mate, great songs, great band.” Mark just nodded. I was sitting there thinking, “They’re my fucking songs! It’s my band! I produced the record!” But I didn’t say anything. I just thought, ker-ching! I get the publishing. But I hate it.’

Since her days in Belle & Sebastian, Campbell has often been described as ethereal. It’s a term she still finds infuriating because it’s used to describe women and not men. Yet it’s hard to reject out of hand: her voice has a wispy, heavenly quality, particularly when set against Lanegan’s deep, emotive growl, and she has always been a daydreamer. ‘I don’t think I was physically present in my body until I was about 25; I was up in the clouds because the clouds were better.’

Campbell might still be a dreamer, but she is also absolutely focused on her music, which she takes terribly seriously. We spend a long time talking about the music her parents listened to – Led Zeppelin, the Stones, Fleetwood Mac and Barbra Streisand – and the brilliance of Bob Dylan. ‘I’ve got a problem right now because people keep asking me about the modern music I’m listening to and I’m not listening to any! I only want to listen to Dylan.’

Suddenly she starts to giggle. ‘Bob Dylan bought a house in the Highlands a few years ago and I was considering getting a job as his cleaning lady. I think he’d be on to me pretty fast. I’ve heard he doesn’t really like people who like his music. What’s all that about?’

Is that the ulterior motive behind the fantasy move to the Highlands? She screams with laughter. ‘No! No! I won’t be stalking Bob Dylan!’

So, it seems, the recovering drug addict will have to do. ‘When Mark is standing next to me on stage, we may not even look at one another but it’s like communing with God.’ She pulls the mac tight and smiles. ‘Sometimes we do stinkers but when the gigs are good, I feel like I was born to do this.’

· Sunday at Devil Dirt is out now. Isobel Campbell and Mark Lanegan’s UK tour starts on Tuesday at the Shepherds Bush Empire, London W12