The Secret Sisters, Bush Hall, London

Laughing and joking with the crowd, at ease on stage, you'd never guess that less than two years ago Laura and Lydia Rogers had never been on a plane, let alone performed in front of a live audience. The sibling duo, who hail from the perfectly Bible-Belt-sounding Muscle Shoals, Alabama, formed The Secret Sisters after elder sister Laura (who handles lead vocals) was spotted at an impromptu Nashville audition. Los Angeles beckoned and their self-titled debut album of sweet harmonies and country charm (recorded, in faux-1950s fashioned, without any digital equipment) was born.

At Bush Hall in west London, they open with "The One I Love Is Gone", a heartbreaking lament for lost love, before unleashing a girlish scream and warming up their idolatrous red neck-loving fans with a belted-out take on country classic "Why Baby Why".

Their music evokes the golden age of honky-tonk by combining self-penned tunes and country classics by the likes of George Jones and Hank Williams. And without a band – only a dark red curtain and two guitars to complement the Victorian venue's restored walls and chandeliers – they are pared-back country to its extreme.

Fresh from a tour supporting Bob Dylan and Elvis Costello, and a spell in Nashville playing alongside Costello, Elton John and actor-singer Jeff Bridges, the sisters are at the end of their British tour but show few signs of fatigue (they do hit the odd bum chord). Laura is the chattier of the two, at times more a comic than a musician as she jokes with the crowd about the troubles of sharing small British hotel rooms with her sister for weeks on end.

They go on to offer little cheer but much charm with a take on Hank Williams's "Your Cheatin' Heart'", and their own track "Tennessee Me".

The girls learned to harmonise to the likes of the Everly Brothers and Doc Watson in their youth so boast authentic country credentials, but seem to be trying a little too hard to conform to a historical musical stereotype. There's obviously a market for their oh-so-innocent chatter, 1950s gingham attire and "authentic" laments, but it's the duo's raw talent that shines through. Their label may be marketing them as an anti-modernist group "sounded and true" in "grounded wisdom", but it's their siren voices that leave me spellbound. They are back in the UK for the festival circuit this summer, make sure you check them out.