Othello, Trafalgar Studios 1, London

To overcome his allergy to Shakespeare, Lenny Henry took drastic measures. He agreed to play Othello – in Barrie Rutter's production which opened at the West Yorkshire Playhouse earlier this year and has now arrived in London. Consider the magnitude of his courage. Henry is a stand-up comedian; Othello is a tragic hero who is not overburdened by a sense of humour. Henry has had to find his (metrical) feet with the iambic pentameter; Othello is, of all Shakespeare's protagonists, the one who is most self-consciously a verse-speaker, turning up the volume on his verbal music as a defence mechanism against the insecurities of his position.

The first thing to say is that never for a second does this performance feel like some job-swap stunt. Henry is possessed of a towering presence and a sonorous delivery. He also naturally radiates goodness, which is handy in a reading of the role that stresses Othello's nobility rather than the alternative view of him as a self-dramatising egotist who is riding for a fall. Henry is, however, periodically inclined to rush his lines, so that you lose a sense of their rhythmic pulse and his Othello never comes across a man who sometimes needs to take refuge in the tranquilising sound of his own voice.

But that's partly because the production fails to give, in the earlier scenes, an adequate indication of the strain he's under. The hero's marriage to Desdemona (Jessica Harris) begins by looking almost complacently easy in its happiness. Othello publicly lifts his feisty little spouse off her feet and twirls her in his arms – a charmingly unselfconscious gesture, but there are too few tremors of the riskiness inherent in this brave union of opposites, or any feel of the added pressures that come from being, as newlyweds, swept by war to Cyprus.

Despite some winning performances (Conrad Nelson's lean, mean Iago flashes skilfully between social plausibility in the mess and seething private poison in the soliloquies), Rutter's production is uneven, drably designed and costumed. Yet it has a peculiar impact that derives both from our knowing that the well-loved Henry is a Shakespeare novice and from his extraordinary feat in persuading us to forget that fact. For those of us barricaded in our trite little comfort zones, his is a morally inspiring achievement.