Lost in the stars, Queen Elizabeth Hall, London

It is quite astonishing to look back and see what made the Broadway stage in the 1940s. It was a time of great daring and innovation when the boundaries between musical comedy and opera were less defined than they've ever been. Kurt Weill's final show for Broadway Lost in the Stars – his musical adaptation with Maxwell Anderson of Alan Paton's novel Cry, the Beloved Country – would be lucky to make off-Broadway today. And yet there it was – a deeply compassionate drama of division and reconciliation in apartheid South Africa playing the capriciously named "Great White Way" in an attempt to prick America's own racist conscience. And it took a Jewish refugee from Hitler's Germany to do it.

Lost in the Stars is an undeniably book-heavy, sometimes laboured, music drama where the play's very much the thing and the shattering final scene is denuded of music to lay bare the potency of the words. Stephen Sondheim was the last person to dare to do this in a piece of music theatre when he, too, gave the stage to his book writer John Weidman in the closing scene of Assassins. As was the case there, the chorus – or better yet the ensemble – has the first and last words in Lost in the Stars, for they are the witnesses and commentators and makers of history in this "musical tragedy" and as such the backbone of this Southbank/BBC Concert Orchestra semi-staging. Mary King (vocal coach and casting director) should be applauded for nursing a richly-diverse group of voices through this difficult, searching, angular music.

It isn't an easy piece to bring off in what must have been limited rehearsal time, but how good to experience it at all, and in its original and so wonderfully Weillian orchestrations. The sepia colorations with oily clarinets and saxes, not to forget accordion, were duly savoured by conductor Charles Hazlewood and there were vocal glimmers, too, with Tsakane Maswanganyi's Irina plumbing the soul singer in her operatically-inflected numbers "Trouble Man" and the enduring "Stay Well".

The title song is one of Weill's most glorious creations and if one wondered why Clive Rowe had been cast as Stephen Kumalo when this and so much else in the score lies too low for him, the answer came in that final scene when he and the wonderful Edward Petherbridge stunned us into a numbed silence as the seeds of reconciliation were tentatively, painfully, sown.