Christopher Sergel’s well-established adaptation of Harper Lee’s To Kill a Mockingbird may not solve all the problems of transferring a novel to the stage, but this new West Yorkshire Playhouse/Birmingham Rep production certainly delivers the goods in terms of emotional power and moral truth.

To Kill a Mockingbird, as generations of GCSE students will happily recall, combines two stories in such a way that each informs and nourishes the other. Two children, Jem Finch and his sister, Scout (a lightly fictionalised Lee), grow up amid a series of entertaining adventures and moral lessons in 1935 Alabama. The interwoven narrative concerns the trial for rape of Tom Robinson, a patently innocent black man, with the children’s father, Atticus, facing the impossible task of persuading a Southern white jury to acquit.

Converting 300 pages to a 2 ½ hour stage play is not easy, but Christopher Sergel’s decisions do not always convince. With 18 named characters, it seems a pity that no place could be found for the alternative moral influence, Aunt Alexandra. Sergel wisely cuts Scout’s discursive narrative (giving some of the background information to neighbour Maudie Atkinson) and moves straight in to the Robinson case, but the opening sequence with assorted characters stating their views and commenting on their neighbours has a stagey Our Town-ish feel to it. The children’s fantasy games about Boo Radley are oddly undeveloped. However, all these reservations disappear with the trial itself and its aftermath, the long-awaited appearance of Boo being beautifully handled.

With the aid of Simon Higlett’s atmospheric set (wooden house-fronts, porches, a swing and Boo’s tree, with a simple and effective court-room conversion) and a moving use of spirituals, blues and work-songs, Michael Buffong’s production is always truthful and involving. He draws sympathetically understated performances from Helen Ryan (Miss Maudie), Andrea Harris (the Finches’ maid Calpurnia), Vinta Morgan (Tom) and many others, with Ged McKenna (a hair-trigger Bob Ewell) and Sally Tatum (his downtrodden and self-loathing daughter) perfect as Tom’s accusers.

Duncan Preston brings out all the rumpled humanity of the play’s unlikely hero, Atticus Finch, never straining for effect, but moving powerfully through the gears at the climax of the trial, followed by the agony of the attack on his children. As for those children, despite Bettrys Jones’ remarkable performance as Scout, the decision to play 9-12 year olds by adults creates some problems as well as solving others: it’s certainly odd to see the Finches’ friend Dill so much bigger than even the adult Truman Capote, his acknowledged model.

- Ron Simpson (reviewed at the West Yorkshire Playhouse)