Barbara Dickson is full of surprises. "I'm a great prog girl," she tells me when I ask her what music she listens to in her own time. "When I was a pop star I never listened to music radio. I listened to Radio 4 and I listened to the prog people and rock.

"My friend Troy plays in a band called Night Wish who are a Finnish symphonic metal band and they are just glorious."

Yes, we are talking about that Barbara Dickson. The Barbara Dickson we know so well from singing songs from Evita and duetting with Elaine Paige. The Barbara Dickson who has won awards for West End turns in Blood Brothers and Spend, Spend, Spend. Turns out, at heart, she's a bit of a rock chick.

But then if you still think of her as the woman who used to turn up on The Two Ronnies or appear in big shoulder pads and big hair on Top of the Pops you just haven't been paying attention.

The truth is Dickson, who will turn 70 later this year, has spent the last couple of decades redefining what she does, as anyone who goes to see her on tour will realise.

"About 1990," she says, "not long after I Know Him So Well was a success, I said to myself: 'Right, I don't want to be a middle-aged pop star because I think that's vaguely undignified. I don't see myself in that way. I like pop music but I'm not prepared to just sing pop music. I've got to try and do something that plugs into what I learned as a young person.'"

When she was a teenager in Dunfermline at the end of the 1960s Dickson was a folk singer on the circuit and so it was to folk that she returned in the 1990s.

"I never took myself that seriously as a pop star," she says. "I always thought the folk police were going to come along and say: 'excuse me. Can we have her back now?'"

She was always something of a reluctant pop star anyway, she says. "I could never have been like Madonna. I could never have played Las Vegas. My management would have loved me to have played at Las Vegas. I could never have done that because I would never have believed that I should have been there."

These days in concert Dickson sings traditional Scots songs, maybe the odd number by the likes of Randy Newman or Tom Waits and retooled versions of the songs that were hits way back then.

"I only had a few hits," she says modestly. "Answer Me was lovely. Another Suitcase in Another Hall is a bit twee as a record, but it's a nice song. I sing that song with an acoustic guitar and it's really touching. January February is a great pop record. I don't do I Know Him So Well because it doesn't fit with what I do and it's a duet so I don't feel beholden."

If anything, she says, performing on stage is a lot more fun now than it was when she was at her height of her fame

"When I was at the height of my powers I didn't enjoy playing as much as I do now because there was too much pressure. There was pressure to be brilliant every time people came to see me, because they were coming in such huge quantities. It made me nervous and worried and I think that I was worried about living up to what they thought was my reputation."

Not that she regrets her years at the top. "It was good for me. The only lasting legacy was everybody knows who I am. Now they might not like me, but you never have to explain who Barbara Dickson is."

And her fans have come with her on the journey from from Evita tunes to murder ballads. "It's a rocky ride," she laughs.

"Gentlemen of a certain age have always rather liked me. Even now there are husbands knocking 70 hiding behind pillars in foyers up and down the country who are too shy to come up and say hello to me, which is really charming."

There have been other changes in Dickson's life in the last couple of years. After her three sons moved out the family home in Lincolnshire Dickson and her English husband Oliver decided they needed a change of scene. That was an excuse for Dickson to return to her roots. She owned a flat in Edinburgh for a few years but in 2015 she and her husband finally moved to the Scottish capital.

"When he first came to Scotland in the early 1980s Oliver said: 'I'm not going to Scotland you can't get a decent pint there.' But now that's changed," she laughs.

And Dickson couldn't be more delighted. "I have come full circle."

"I don't feel any more Scottish but I love Scotland. That's why I'm here. I've put my money where my mouth is."

Barbara Dickson plays the Royal Concert Hall, Glasgow on March 1.