In what has been the year of young women with synthesisers, it's impressive that few look as instantly iconic as a 56-year-old woman playing a guitar. Smouldering in black, instrument firing from her hips and singing with her head tilted back, Williams radiates such outlaw cool that it's surreal to think that she's currently enjoying mainstream success with her latest album, Little Honey, in the US top 10.

Williams could inspire a new generation of young women to play guitars or perhaps tempt her fiftysomething peers to ponder casting their grandchildren aside to rock; but few could match her extraordinary voice. Quite what enables it to lie exactly between yearning and regret is uncertain, but perhaps the clues lie in a colourful life. Telling of her years of struggle – "I was told I was too rock for country, too country for rock" – her Grammy-winning songs tell of "hero-inn" and Drunken Angels, as she casually rattles off killer one-liners like: "I wanna feel your breath, even though you like to flirt with death."

Williams is disgustingly cool, yet she gives everything emotionally to these songs, singing Memphis Pearl (inspired by glimpsing a woman rifling through rubbish, "a sight that's since become all too common") with real empathy. Backed by the terrific Buick 6, the two-hour show leaps from the heartbreaking Over Time to the playful Honey Bee, in which she confesses that she has "got your honey all around my tummy".

"We're bad-ass and nationwide", she announces after almost two hours, and it would take more than a team of sheriffs to stop her now.