BBC Folk Awards best duo winners Josienne Clarke and Ben Walker to play Black Swan in York

Such has been their rise that Clarke, from West Sussex, and Walker, from Worcestershire, have now signed to Rough Trade, with a new album on its way in the autumn and their Rough Trade Sessions cover of Nina Simone's For All We Know available to view on YouTube.

The duo first performed their songs of everyday love and loss to one woman and a bored dog at London acoustic nights in 2009, but the release of their first two albums, One Light Is Gone and The Seas Are Deep, led to interest growing in discerning pockets of the blogging community.

Progressive Macclesfield folk musician and producer Jim Moray persuaded them a far bigger audience would appreciate their classically instilled traditional songs and self-penned lovelorn ballads. Although Clarke was initially sceptical that the folk and roots scene would welcome outsiders, the end-of-year polls and nominations that greeted their 2013 album Fire & Fortune would prove her gratifyingly wrong.

Their latest album has drawn even more plaudits, earning five-star reviews across the board. Entirely self-financed, self-produced, self-arranged and released on the Folk Room label they co-run, 2015’s Nothing Can Bring Back The Hour was an ambitious realisation of everything Clarke and Walker had planned when they met seven years ago.

Much of their music is characterised by lush chamber ensemble orchestrations, but what sets them apart is the combination of Clarke’s emotionally affecting voice and Walker’s intricately expressive, adroit guitar technique. They cite Sandy Denny, June Tabor, Nic Jones and French-Algerian guitarist Pierre Bensusan as influences but their sound is their own.

Although Walker studied classical guitar from childhood and Clarke is a classical music degree dropout, both stress they are “bog standard comprehensive school kids” who did not benefit from a conservatoire education. To emphasise the point, Clarke has been known to quip: “We’re not posh, just pretentious."

This self-deprecating humour is key to their live shows where Clarke's often sad and poetic lyrics, and the death and doom-laden nature of the old songs they interpret, are countered by an awareness of the need to lighten the mood. Consequently, the melancholia, mirth and sheer beauty of their performances has taken them to such auspicious stages as Cambridge Folk Festival and London’s Purcell Rooms, a far cry from the pub back rooms where they began.

After their rendition of The Banks of The Sweet Primroses at last year's BBC Radio 2 Folk Awards, BBC 6Music presenter Cerys Matthews invited Walker and Clarke to participate in the National Theatre’s 2015 production of Our Country's Good. Timberlake Wertenbaker's play featured two of the duo's compositions in the Olivier Theatre run from last August to October.

Tickets for their 7.45pm show on May 26 cost £11, concessions £10, on 01904 632922, at blackswanfolkclub.org.uk or at wegottickets.com/event/341686