Surely Ewan McGregor was kidding when he said in a recent interview with The Times that playing Iago was more challenging than motorcycling the length of Africa or whizzing low over Scots mountains in a Tornado. He has, so to speak, taken command of the handlebars or joystick of the role and steered his way through it with the macho assurance of an Evel Knievel or a Red Arrow pilot.

Also, less happily, with their speed. There are times when you feel that Knievel wouldn’t overtake McGregor as he scrambles over pauses as if over Ugandan chasms, nor would the Royal Air Force beat him as he roars past syllables, leaving Shakespeare as far behind as Ben Nevis. As a result, you believe that his Iago is quick of wit and stunningly swift when it comes to improvising new disasters or turning random events to his advantage; but the odd thing is that he is most powerfully eloquent when he is not speaking. To watch McGregor simply standing at the back and directing his laser eyes at Chiwetel Ejiofor’s Othello, Kelly Reilly’s Desdemona or Tom Hiddleston’s Cassio is to believe that they are in the clutches of an authentic monster.

And last night all three of his victims proved as adroit with Shakespeare’s language and emotions as one had expected, given that Michael Grandage was directing, and doing so with his usual flair, care and respect for the text. Was Ejiofor a bit lacking in Othello’s “fury”? If so, I didn’t care, because he wasn’t one of those oversized generals who majestically roar, but a slim, lithe, very human Moor, wonderfully warm when he’s embracing a Desdemona he clearly adores, agonisingly bewildered when he’s convinced that she is adulterous and genuinely tragic when he’s wailing with grief over her deathbed.

Grandage’s handling of the relationship between that wife and her supposed lover is particularly effective. You never doubt that Reilly’s Desdemona is innocent, but she’s a touchy-feely girl who sinuously yet unselfconsciously exudes sexuality. And Hiddleston’s Cassio is equally demonstrative, an outgoing, emotionally generous young man for whom it is natural to kiss, hug and stroke, as he strokes Reilly’s cheeks. In an era when actors tend to suggest that Cassio is in love with Desdemona, he manages something unfashionable and difficult: he’s enchanted enough with her to arouse Othello’s jealousy but never for a moment does he boil with desire.

And McGregor? Well, Laurence Olivier once said that anyone who had served in the Navy or, like him during the war, in the Fleet Air Arm, could easily believe that Iago wanted to destroy Othello and have Cassio killed as an extra treat. To sit in the wardroom and look at the sullen, bitter faces of men who had been passed over for promotion was to know that Coleridge was wrong when he famously used the phrase “motiveless malignity” about Shakespeare’s most vicious villain. And especially when he’s talking of the callow foreigner who is Othello’s lieutenant and his senior officer, you feel that this Iago, with his very ordinary body language but ultra-scary eyes, has a big, big grudge.

McGregor is, rightly, more inscrutable than that. There are times when his diction is fine and they are often the right ones: “I hate the Moor,” he declares, this time putting enough space between each word to deter even Knievel. He’s vigorous, hard, mean and he does hate, really hate. Hate enough to give us Shakespeare’s play as it poignantly, painfully should be.

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