Isobel Campbell on her new album Hawk and why her unlikely alliance with grunge veteran Mark Lanegan works so well

THE last time I was kept waiting by Isobel Campbell she was 45 minutes late, a problem complicated by her refusal to carry a mobile phone.

Today she effortlessly achieves a new personal best of 1 hour 10 minutes, this despite now owning a phone, which at least enables us to communicate by text (Me: "Bored reading Naomi Campbell story – where r u?"). Finally she shows, a seductive riot of blonde curls and melodramatic eyeliner. "Really sorry," she says, "but I lost my handbag."

It is very difficult to be angry with Campbell, however, or to accuse her of behaviour more befitting her supermodel namesake, because the former cellist and muse of Belle and Sebastian, who now sings with grunge veteran Mark Lanegan, gives you everything you want from an interview. She's funny, insightful and honest in a way that can mildly stun you, such as when she admits: "I know I drive people nuts. In the last eight years I've had six... no, seven different managers."

And not for her the usual artist evasiveness over where her songs come from. Of the new album Hawk, much raved-about as the duo's best, she reveals: "I thought I was going to become a wee wifie chained to the kitchen sink, to marry a builder and spit out his babies, and I thought I wanted that. But it's not going to happen now. That's what these songs are about."

After the first album of folk-country duets with Lanegan, prompting the first comparisons with Lee Hazlewood and Nancy Sinatra, everyone thought them such an unlikely pairing that it would probably never be repeated – and Campbell agreed, not least because they had recorded their vocals 5,000 miles apart. But she thought she'd chance her luck anyway, asked if he'd work with her again, and he replied: "In a heartbeat."

For album number 2 she persuaded Lanegan, a recovering drug addict, to leave his adopted Los Angeles and sing with her in the same Glasgow studio, but by the end she had invested so much time in the project – two years to his nine days – and so much of her own money hiring orchestras that friends cautioned her against a third outing.

"One very dear girlfriend thought I wasn't getting out of the partnership what I was putting into it," says 34-year-old Campbell as she orders a (very) late lunch off Sauchiehall Street. "So I felt like I was cheating on her when I decided to call Mark." Campbell writes, arranges and produces their records. "They're my folly and I do what he calls the heavy lifting." So how many days did he give her this time? "Oh, five – and two of them he was in a foul mood. At the end, he said: 'Isobel, you know I'm a grumpy old shithead – please forgive me.' And I did!"

Campbell always laughs when their relationship is likened to that between a Hammer Horror demon and his damsel. "Mark towers over me, is 11 years older and says I remind him of a girl on his first camping expedition but I'm not intimidated by him – in fact, I'd say it was the other way round. When he didn't want to sing two of the songs I got Willy Mason in. That put his gas at a peep, at least for a while."

How would she describe their relationship? "Mark's like a family member now, although don't ask me which one." Do they send each other Christmas cards? "No, but then I don't send any. I've had a lot of really tough Christmases, like when my parents divorced, and I just spend them worrying about everyone. This one's going to be tough for a lot of people isn't it? Maybe the government should just cancel it, give everyone an orange."

For all his faults, however, Lanegan must have seemed like Campbell's rock two years ago when the rest of her world convulsed. Her band disintegrated; she lost her guitarist and was forced to sack her drummer. Her beloved grandmother died. And the man she thought she was going to marry walked out on her.

"Almost right away he said: 'You're mine forever.' I was like 'Yes, yes,' which wasn't me at all; I'm the kind of girl who, first date, brings a girlfriend along. And for a while it was intense and wonderful. But he dumped me. I was brokenhearted, completely destroyed. Then, almost right away, I dived straight into another relationship, which of course turned out to be another disaster."

Due to tour, Campbell wanted to cancel the shows. "I couldn't stop crying. I went brunette. But Mark phoned and said: 'I've flown a long way. We're doing this.' The snot just poured out of my nose after that. If you're in a vulnerable way, the road really isn't the place to be – it's just so lonesome. And that time reminded me of when I left Belle and Sebastian – lots of what I call my 'Judy Garland moments'. I should have stayed at home with a hot-water bottle."

When Campbell eventually made it back to Glasgow, she decided she no longer wanted to be there. Disillusioned by everything that another horrible Christmas had thrown at her, she caught a plane to Tuscon, Arizona. "It was brilliantly sunny. I saw hummingbirds and wept tears of joy." Friends took her in and helped put her back together. She house-sat at a swish pad with a pool and a two-week stay turned into six months.

"Through all the chaos and heartbreak and soul-searching I met some wonderful people. I learned how therapeutic kids can be and enjoyed my best-ever Valentine's Day with a five-year-old boy. I also met some wonderful musicians, such as Victoria Williams, and it was while hanging out with her that I think I had a bit of an epiphany.

"I thought I wanted to be that builder's wife but maybe that's not me after all and maybe, like my mum always says, I'm married to my music." Not surprisingly, the songs that would make up Hawk came quickly. And before she knew it Campbell was phoning Lanegan again.

Part of the album was recorded in an LA studio which, unknown to Campbell, had once been used by Hazlewood and Sinatra. "An old engineer told me: 'Lee would've dug you,'" she says. But, while respectful of the ghosts of that session, she didn't let them overpower her own. The double-act with Lanegan is its own thing now: elusive, maddening, sensual, right.

When I point out that those five-star reviews continue to speculate on the likelihood of the studio being kitted out with a bed, Campbell chuckles. "It's a damn weird relationship, for sure, but Mark and I know what we do well together and that's sing."

As her timekeeping confirms, her life is complicated enough.

Hawk (V2) is out now. Isobel Campbell and Mark Lanegan play Glasgow's ABC on 8 September