There are currently five, and soon will be six, National Theatre productions on in the West End. Meanwhile, Broadway - which has taken such plays as Closer, The Invention of Love and Amy's View from the National in the past few years - will soon have Trevor Nunn's National Theatre staging of Oklahoma! on its boards, too.

But the National doesn't merely export; it also occasionally imports. Last year, it brought August Wilson's Jitney from off-Broadway to the Lyttelton, for a run that has just seen it deemed the year's best new play in the Laurence Olivier Awards. Now, there's another arrival from off-Broadway, The Syringa Tree, still running there but now imported to London with its original star and author, Pamela Gien, recreating her award-winning performance.

The play, set in Johannesburg in 1963 and told from the point of view of six-year-old Elizabeth, is obviously a keenly personal piece by the South African-born actress and playwright. Both beautifully observed and observant, it looks at the early days of apartheid through the innocent eyes of childhood to evoke the multiple contradictions and conflicts of being brought up under that policy, and Gien also draws on a rich tapestry of other characters to weave her compelling theatrical spell.

But as someone who was myself born a year earlier than the play's setting and in the same place, I was, surprisingly, not entirely spellbound. While acknowledging the undoubted honesty of the writing and the palpable sincerity of the performance (and Gien's amazing facility for instant switches of character), the work has also become a little too slick and meticulously rendered. She has been performing the play for over two years now, and the performance lacks the spontaneity it must have once had. The performer's emotions now seem manufactured, not inhabited; meanwhile, the play to our emotions seems sentimentally calculated, not earned.

What a pity it is not to have seen this show sooner in its life, for it's a shame to be made to feel cynical about something that was born of integrity. Though I wanted to engage passionately with it, I was unmoved by The Syringa Tree.

- Mark Shenton