Crime follows Duff into new play written specially for her

The result of this collaboration is Ciara, a solo piece in which Duff plays a woman who runs a successful Glasgow art gallery, but who also happens to be the daughter of a just-deceased big city crime lord.

"David told me he wanted to write something about Glasgow," says Duff of the roots of the play that now forms the flagship production of the Traverse Theatre's Edinburgh Festival Fringe season. "That was in 2010, then in 2011 he came back, and we worked quite closely on the play. It was so exciting being part of that process, and what we've got now is this piece about a woman in her fifties who has effectively legitimised her father's ill-gotten gains. It says something about the relationship between the art world and the underworld, which has always existed, but it's also about grief and loss, and is an incredibly moving family story as well."

Perhaps because she's been on the other side of the law as Detective Constable (then later Inspector) Jackie Reid in Taggart for more than two decades, Duff seems to be able to find it easy to apply the necessarily forensic eye for detail in finding out what makes her character tick.

"She's a tough cookie," Duff says of Ciara. "She's smart. I think she's got a lot going for her, even though she's grieving for a lot of things. She's certainly grieving for the loss of her childhood. She had an extraordinary childhood, during which she was very cosseted. She was a princess, and when princesses grow up they become some kind of royalty.

"She also has this incredible need to tell her story. She says from the start that she doesn't care if the audience feels sorry for her or not, but she also has this incredible need for love, even as she's coming to terms with her grieving. She's married, but you find out that she's very much alone in the world. Her mum's not around, her brother's not around and her dad's not around, and you discover she's quite a lonely soul.

"There's people she has lunch with, but she has no real friends she can talk to. That's why she seeks people out to tell her story. The people who live in that world she grew up in. There's not many people you can talk to about it."

Duff was last seen on stage in the Borders-based Firebrand company's revival of Rona Munro's women's prison-set play, Iron. Duff's turn as a lifer won her the Best Actress award at this year's Critics Awards for Theatre in Scotland.

It couldn't have come at a better time," Duff admits. "After 30 years in the business, I must be doing something right."

Prior to Iron, Duff did Good With People, and previously appeared in another solo work, Karen McLachlan's play, Just Checking. The latter was produced by Duff's own company, Datum Point, which also co-produced Good With People, and is now joining forces with the Traverse again for Ciara. While there have also been roles with the National Theatre of Scotland, all of the plays named above found Duff sticking her neck out in a series of meaty roles where, after 21 years of Taggart, she could so easily have played safe.

"I keep thinking, oh, my God, that was a big number," Duff says. "Every time I've done a big, chunky piece, the experience propels me onto the next thing. So since 2009 I've constantly been in preparation for projects. I really work hard, and I decided I was going to put myself on the line in some way. I turned 50, and you'd think there are no parts for 50-year-old women, but I've been seeking them out, and embracing everything that comes my way.

"I never thought one job would last 21 years, and now, I could probably get a job that would earn me lots more money, but the Traverse gave me my first ever professional job, and, it sounds grand, but I suppose I want to give something back. And when someone like David Harrower comes along and says he is thinking of writing something for you, it's very flattering. I need to be creative, and be inspired by texts, so it's all a bit of a buzz. Performance is one thing, but it's the process to get that which in some ways makes things more interesting. It's really connecting to people that I enjoy."

By Duff's own admission, it hasn't all been plain sailing.

"When I did Iron," she remembers, "we had three-and-a-half weeks to prepare, and I almost did a runner. I thought, okay, I'm in Hawick, no-one will find me. That play's 102 pages long, but with a new play you've always got a big white script. With Iron, we were working with the published play-text, and because that's so small, you under-estimate how many words there are."

Despite her anxieties, Duff gave a storming performance, hence the much-deserved award. Beyond this too, Duff is in full possession of a canny pragmatic streak that suggests she's more in control than she lets on. This manifests itself most clearly via Datum Point, and her whole approach to co-production and collaboration in austere times.

"This is something I want to do," Duff says of Datum Point's ongoing set of co-productions. "We all have to think about doing theatre in a business-like fashion. Business is a dirty word, but we have to talk ourselves up. We have to make theatre something that people want to leave the house for."

With Duff onstage, Orla O'Loughlin's production might well be that sort of theatre.

"I don't think this will be a show-off piece," Duff says. "There's not a lot of movement. I let the words do it for me. My thoughts about Ciara are that it needs to have a long life. It needs to come to Glasgow. It's like Glasgow rock. It's got Glasgow imprinted all the way through it.

"The Edinburgh Festival audiences will take it in one way, and that's great, but this play shows Glasgow warts and all, and Glasgow audiences are used to that.

"It's this incredible exploration of the Glasgow art world. Some people are frightened of art if it doesn't match their furniture, but the play looks at how artists work, and what art means to people in a world where the criminal element and what we call the cheese and wine element sit cheek by jowl."

Ciara, Traverse Theatre, August 1-25 www.traverse.co.uk