Hampstead Theatre | ★★★★✩

Nell Leyshon’s play with folk songs soars on the utterly mesmerising voice of actor Mariam Haque who could — should — make an album of the music.

Meanwhile, actor Simon Robson may be getting hits of deja vu while playing his latest role. In Leyshon’s absorbing four-hander Robson plays the upper class Cecil Sharp, a role not dissimilar to Henry Higgins whom he played ten years ago in a production of Shaw’s Pygmalion.

Both Sharp and Higgins have an interest in the way the working classes express themselves. Although whereas the fictional Higgins was interested in language, the obsession of the real-life Sharp was music, particularly folk songs which he saw as a neglected resource that had the potential to inspire English composers, if only they knew.

In 1903, the year Leyshon sets her play, Sharp was principal of the Hampstead Conservatoire of Music which was located in the Italian villa now occupied by the Central School of Speech and Drama, located opposite this theatre.

But rather than setting the play in Hampstead, Leyshon opts for the village Hambridge in Somerset, not far from where the playwright was raised.

In this version of events it was while staying at a friend’s house in the village that Sharp discovered Louie Hopper (Haque) a walking repository of folk songs taught to her by her recently deceased mother.

The play opens just after the death. Louie (Mariam Haque) is wracked by grief, her more pragmatic sister Lucy (Sasha Frost) less so. They must continue to eke out a living making gloves and Louie must take the temporary job as maid in the local rectory. It is here she meets Sharp and the play starts in earnest.

Roxana Silbert’s pacey direction cuts through the class differences between the two. The casual patriarchal authority of Robson’s musicologist is given short shrift by Haque’s remote, monosyllabic village girl. Her awakening is triggered by Sharp’s interest in her music and the play blossoms with their collaboration and Louie’s at first reluctant renditions of her late mother’s songs.

Leyshon’s plot keeps us interested in the fate of her characters with some teasing questions: Will the affair between Louie’s sister Lucy and restless local man John England (Ben Allen) end happily? And might there even be a class-vaulting romance between the illiterate Louie and upper-class Sharp?

Yet the real drama here lies in differences that emerge out of the collaboration — her innate musicality verses his stuffy musicology. The clash climaxes when she realises that by writing down music that is sung in fields and meadows Sharp is petrifying it onto pages where it can no longer evolve. What he sees as an act of preservation, she sees as a kind of death.

With this dilemma the Hampstead’s intimate new writing stage crackles with argument. Less convincing however is where they disagree about nationhood. Sharp’s search for ‘pure’ English music is motivated by patriotism and when Louie criticises his sentiments she suddenly sounds awfully like a liberal, urbane playwright who lives in 21st century London, much like Leyshon.

Still, when Haque sings nothing else matters. She has a voice that conjures generations for whom song was their only heirloom. They are lucky to have her.