'Being Scottish, I find Burns Night's always an excuse to have a whisky and a good meal and to get together with any Scottish friends you have, no matter where you are,' says KT Tunstall, the headlining artist at the eighth edition of Big Burns Supper, the winter festival which looks to honour the Bard of Ayrshire Robert Burns in the area where he spent the final years of his life in the late 18th century. The festival's bill also includes music from Frank Turner, Colonel Mustard & the Dijon 5, Tide Lines, Craig Charles' Funk and Soul Club and more, with comedy from Ed Byrne, an LGBT disco performance party at Queer Haggis, and much more.

Tunstall has memories of a Burns supper in recent years at a restaurant in Los Angeles, where she now lives. 'Just stabbing this massive haggis with a knife and a bunch of American people being completely horrified and backing away,' she laughs. 'This is the first year for a while that I've been in the UK for Burns Night, just seeing sunshine in winter was part of why I moved to LA, as I'm sure you can imagine. I usually try and make sure I'm over there at the end of January, but this time I'm in the UK and when the organisers (of Big Burns Supper) sent an invitation, it seemed like a really good fun thing to do.'

How much does she know Burns' work herself? 'I've just grown up knowing it,' she says. 'I mean, you hear varying reports of what kind of man he was … But he certainly left this legacy on Scottish poetry, and I do enjoy "Ode to a Haggis". I've read it at all sorts of Burns nights, from an event with Ewan McGregor and Sharleen Spiteri, to doing it at a pal's house in London just before I got my record deal. We sat about on the living room floor with a bunch of people from all over the world and we all took a stab at reading it, it was ridiculous.

'I remember studying "Tam O'Shanter" at school and thinking it was like Shakespeare, in that it's more fun to do it in that academic way so you understand what's being said. I don't know what half the words mean, so I really enjoyed doing it that way … and I found it's quite a nice poem, actually.' Does she ever dip into the rest of Burns' canon on Burns Night? 'I don't think anyone can be arsed with anything else, after reading all that! It's time to have a drink, you've gotten warmed up for it.'

Immediately after the Big Burns Supper, Tunstall is heading to Mexico for Brandi Carlisle's all-female Girls Just Wanna weekend festival, then after that she'll be playing her headline UK tour, visiting venues like Glasgow's Barrowlands and Dunfermline's Alhambra, with an all-female band which includes sometime Honeyblood and Mogwai drummer Cat Myers. 'Then there's a bit more US touring, a bunch of festivals in the summer,' she says, 'and after that I'm going to try and concentrate on finally getting the new album done.'

The rapper and author Darren 'Loki' McGarvey makes the point in his live show that mainstream Scotland's taste for radical and subversive poets is amplified when – in Burns' case – they've been dead for more than two hundred years. In which case, it's intriguing to search the BBS line-up for anyone who might reflect some of Burns' radicalism; and while Frank Turner is no stranger to making political points himself, it's his support act, Leicester's Grace Petrie, who is coming to be increasingly referred to as a forerunner of a new generation of British protest singer.

'I write songs about politics from an anti-austerity, left-wing perspective,' says Petrie, 'but I'm coming to believe more and more that all art is political, and it's really important to find the political narratives in all music. So yeah, I'm really excited to be doing this show, because there is that connection. I think Frank (Turner)'s great, yeah, we're probably similar more in the style than the content. We both exist in that space between folk and punk, the music doesn't belong wholeheartedly in either, but it has a foot in both camps.'

In what sense does she believe all art is political, from her perspective at least? 'I'm gay, and as a queer artist even me writing a love song about another woman, for many people that's seen as being a political statement in a way a male singer singing about a woman isn't,' she says. 'So it's very hard for me to separate the two things, and we're living in this incredibly political time, in this tremendously divided country, and one of the major things we're seeing is this huge inequality between the richest people in society and the victims of austerity. If you're writing songs about the world you live in, I find that's very difficult to separate that from politics.'

The effect of addressing these issues at her gigs, she says, is more uplifting than anything else, and it must have the same effect as Burns' words when they were first performed. 'You can move people with a song,' says Petrie. 'Music has an amazing power to help people see they're not on their own in various different struggles. The biggest thing we need to overcome is the idea that you can't change anything when you're just one person – all you need to do is find some people that share your beliefs and you've got a movement, and music is brilliant at working as a conduit to find those people. I think that's a real force for unity and for solidarity.'

Big Burns Supper, various venues, Dumfries, Thu 24 Jan–Sun 3 Feb.