They were written as many as 50 years ago, songs from Scotland which articulated the social and political landscape of a nation and its people.

Their authors could not have imagined how their lyrical snapshots would resonate in a divided country decades later.

Yet as folk singer Karine Polwart prepares to tour her collection of classic Scottish songs spanning half a century, she does so knowing that their appeal has endured beyond simple sentimentality.

The Stirlingshire-born folk singer, a former social worker, will this week play to the biggest crowds of her career, touring her Scottish Songbook album to prestigious venues like Edinburgh’s Usher Hall and the Barbican Centre in London.

Scottish Songbook scored the songwriter the highest album placing of her career when it was released earlier this year, with a mid-week Top Ten placing alongside Lewis Capaldi in the UK album charts, before settling at 34.

The album is a collection of reinterpretations of songs by well-known Scottish artists including Big Country, The Blue Nile, Waterboys, Gerry Rafferty, John Martyn, Strawberry Switchblade and Deacon Blue, performed by Polwart and her band.

Keen to avoid an exercise in jingoism and nostalgia, each song on the setlist has been selected by the singer for its unforeseen contemporary relevance.

Polwart said: “A lot of the songs come from that period between 1983 and 1985, when I was discovering music independently of my parents, taping things off the radio and getting sucked into the idea that these bands were from Scotland and that they were talking about places which seemed familiar. That was a big part of why I got drawn to those songs and a big part of why they still have impact now. They connect to our times, that issue of feeling worthless through worklessness, precarity of work.

“That’s exactly of our moment. You can map the unemployment that results from de-industrialisation with the likes of Ken Loach making a film about zerohour contracts and the gig economy. It’s the same stuff, and it shouldn’t be.

“That’s what’s important to me about performing these songs. It’s not just a romantic trip down memory lane, it’s about saying these songs were about actual people and they resonated with people at the time, and those resonances are still true now. For some they’re maybe even more resonant now than they were then.”

While the work of some contemporary artists such as CHVRCHES also feature in the project, Ms Polwart has interpreted a prescience in songs such as the late John Martyn’s Don’t Want To Know About Evil from 1973 and The Blue Nile’s 1984 song From Rags To Riches.

She said: “There’s something absolutely menacing in listening to that John Martyn song in the era we’re in now, with that question about telling the difference between what’s true and what’s fake.

“With From Rags to Riches, you just need to look at what’s happening with uprisings in places like Chile and around the world. You can’t expect people to live in poverty and for there not to be an impact. In my head that’s a song about freedom, about people rising up and seeing possibility. It makes the hairs on my neck stand up.”

The inclusion of songs by Big Country’s Stuart Adamson and Scott Hutchison’s Frightened Rabbit on the LP and live show is deliberately significant by way of tribute. Both songwriters took their own lives, Adamson in 2001 and Hutchison 17 years later.

“They’re back to back on the album,” said Ms Polwart. “I think they would have loved each other if they were still around, and had a great respect for each other’s music.”

The band have received support from Deacon Blue’s Ricky Ross and The Waterboys’ Mike Scott following covers of their classics Dignity and The Whole Of The Moon, as well as members of Big Country for her take on their 1983 hit Chance. Previous shows included versions of Bronski Beat’s definitive Smalltown Boy and Eurythmics’ Here Comes The Rain Again. Now Talking Heads, Emeli Sande and The Big Dish are set to feature in the upcoming lives shows in Edinburgh, Perth, Aberdeen and London.

“They’ve each been picked for their political resonance,” she said.

Having first performed the songs live at Leith Theatre as part of the 2018 International Festival, the tour will see the philosophy graduate perform to the biggest audiences of her career.

“The Usher Hall is the biggest venue you could fill with my kind of music in Scotland,” she said.

“It’s quite symbolic for me, because it’s 20 years to the week since I handed in my notice as a social worker. I’ve been asked a lot if I’m going to do another album because there are so many songs we left out. I like the idea of a film using only these songs to drive the arc of the story,” she said.

“My kids thought it was hilarious that their mum was briefly up there with Lewis Capaldi in the album charts. There’s no end to what you could do with the songs that weren’t on this album. But this has been a real labour of love, so I’m taking a breather.”