NOT so long ago, KT Tunstall felt burnt out. After months of touring 2013's Invisible Empire/Crescent Moon, a downbeat album written shortly after the death of her father and the end of her marriage, the Scot was hollowed out.

As she told The National in 2016 just before the release of sunshine pop comeback album KIN, there was a time she thought she was "done with the whole thing".

A turning point was The Healer, a vivid, energetic track that featured on her Golden State EP, released in the run-up to the Top Ten-selling KIN. The song was her "reset button", she says.

"There was a feeling that people were saying: 'Oh, she's in her 40s now, that why she's making these melancholy folk records'," Tunstall says. “And I was like: 'hold on a minute, my dad died and I got divorced, that's why I made a record like Invisible Empire/Crescent Moon'. The Healer was to let everyone know I was still very much a driven rocker."

A rerecorded version appears on forthcoming album WAX, released on October 5.

If, as she told another interviewer in 2016 that her "spirit dragged my mind and my body into making KIN", WAX, produced by former Franz Ferdinand guitarist Nick McCarthy, focuses on the body and physicality.

The album's "mission-statement song", she says, is Human Being, an angular, Blondie-influenced track which centres her fiery guitar licks.

"For me the electric guitar is the most physical instrument," she says. "It can be graceful, but with a single touch it can be a wild beast. It can rip a whole in the space-time continuum if you turn it up loud enough."

Recorded in McCarthy's deliberately basic garage studio in London Fields, WAX's trajectory is intended to "mirror our experience as human beings", she says.

"It starts off very vigorously and begins to decay tempo-wise and thematically as it goes on. The Night That Bowie Died is about Bowie dying, and how it made me and everyone feel; reminding you of everyone that you've loved who's gone.

“At the beginning of the second half of the record you've got this song called In This Body, and I feel that's where I am now; in this unexpected spurt in the second half of life."

Now 43, Tunstall has been no slouch in recent months, playing with Simple Minds and The Pretenders on their recent extensive tour. Hearing her hero Chrissie Hynde calling her "inspirational" every night was an odd experience. But Hynde isn't alone in her opinion, with Tunstall being awarded the Inspirational Artist gong at the Women In Music Awards. In April this year, she was chosen as the first ever female grand marshal to lead the New York Tartan Week parade. Role models and representation is important, she says.

For this pre-album gig at Edinburgh's Liquid Rooms, Social Bite's Scotland-wide Sleep In The Park homeless benefit concerts on December 8 and next March's full UK headline tour, Tunstall will be backed by a band of all-female musicians, including former Ash guitarist and frequent collaborator Charlotte Hatherley and Honeyblood's Cat Myers, a ferociously-good drummer recently seen beating the skins for Mogwai.

"All my musician friend have heroes, like Cherisse [Osei] from Simple Minds is a huge Sheila E fan, and I'm a huge Chrissie Hynde fan,” says Tunstall. “All musicians have these touchstone people, often someone of the same gender. So for young girls, I think it's all about that phrase: if-you-can't-see-it, you-can't-be-it. I thought that instead of moaning about there not being enough women in rock music that I would do something about it: employ some bloody brilliant women."