How apt that this beautifully understated almost mythic love story between a struggling Irish musician and a Czech single mother should be staged around the corner from London’s Tin Pan Alley.

As the audience enters, the 13-strong cast of actor musicians are playing a foot-stomping ‘session’ on Bob Crowley’s atmospheric mirrored pub set, and the ensuring action feels more a gig than a musical.

Based on John Carney’s wistful Dublin-set indie movie, and featuring the Oscar-winning song Falling Slowly, the conversion to stage has been lyrically managed by Black Watch director John Tiffany and Kilburn-based writer Enda Walsh.

Fleshing out underdrawn peripheral characters from the film, Walsh, himself a Dubliner, brings a very Irish philosophising melancholy to proceedings, alongside a ‘let’s put a band together from a load of oddballs’ humour reminiscent of Roddy Doyle’s The Commitments.

(Indeed Glen Hansard who wrote the songs played the guitarist in Alan Parker’s film.)

With its undercurrents of emigration, immigration and economic depression, Walsh introduces subtle commentary on the recent implosion of Ireland’s Celtic Tiger.

Zrinka Cvitesic’s Girl is among the Eastern Europeans who moved to Ireland, but were left high and dry by rising unemployment – and a husband who has returned home.

Guy’s girlfriend, like millions of young Irish before her, has emigrated to New York. Grieving for his dead mother and convinced his music has no audience, he’s nursing suicidal thoughts when Girl meets him busking and saves him with a transfusion of hope and energy.

The simple story unfolds slowly, punctuated by Hansard’s folk/rock songs, not all classics, but some gorgeously rendered with expressive choreography and full cast harmonies that fuse Irish and Eastern European folk rock.

It’s intense, emotionally involving, yet never sentimental or schmaltzy, although some might find such a simple unrequited love story frustratingly drawn out.

Declan Bennett makes a moodily, depressive anti-hero mired in fear of failure, Cvitesic offers a delicate blend of rueful sadness and urgent passion that is endearing and moving in equal measure.