Once focuses on a nameless busker played by Glen Hansard, last seen on screen as the ginger, pony-tailed bassist in Alan Parker's The Commitments, now lead singer with Irish rock group The Frames.

Singing his heart out for a few Euros a day, 'the Guy' has moved back to his childhood home above his ageing dad's hoover repair shop, supposedly to help out after the death of his mother but in reality licking his wounds after having his heart broken by a cheating girlfriend.

Enter 'the Girl' (Marketa Irglova), a Czech immigrant taking on a variety of low-paying jobs to support her young daughter and non-English speaking mother while trying to come to terms with her separation from the husband she left behind.

Drawn to the Guy's earnest, emotional songs - belted out in the face of pedestrians' indifference - she draws him out of his self-pitying shell, revealing herself to be a classically trained musician and a kindred spirit.

They are soon collaborating on songs, their mutual attraction hinted at through their writing, but never acted on.

The dramatic crux of the film comes with the recording of a demo CD but there are no passionate declarations, kisses in the rain, or out-of-the-blue, once-in-a-lifetime recording contracts that will whisk them away to fame and fortune.

It is this steadfast refusal to follow any Hollywood conventions that lends Once much of its charm. Defiantly low-budget, with shaky camerawork, occasionally stilted performances and a distinct lack of glamour and gloss, it somehow succeeds as a beautiful and touching love story.

The casting of Hansard and his real-life musical counterpart Irglova is inspired. Their natural performances gel with the film’s documentary style to leave a love story unencumbered by the unreality of a traditional musical and its showy song and dance numbers.

Note to metalheads: if Damien Rice-style singer-songwriters have you reaching for the sick bucket, you might want to give it a miss.

Ruth Ford