Better late than never. In Stratford, much better late than never. Almost two months after Frances Barber fell off her bike, damaging her leg too badly to play Goneril at the appointed time, yesterday saw the official opening of the Royal Shakespeare Company’s big revival of King Lear and, most importantly, allowed Ian McKellen to bring depth, openness and emotional, spiritual and, at times, literal nakedness to the title role he has waited all his life to play.

Trevor Nunn’s production opens with a splendid parade of courtiers in costumes that are mostly modern Ruritanian, at their centre a Lear dressed and crowned like some glittering Orthodox archbishop. But the royal pomp is instantly replaced with a display of royal weakness: a wobbly reading of his decision to abdicate, a half-jokey, half-serious invitation to play love-games, then fulminations and tantrums and invocations of the pagan gods that leave everyone prone and speechless.

There’s plenty of detail in what follows – a hint of the regret over Cordelia’s rejection that he’s already starting to feel when he quavers over his refusal to offer her his “benison” – but also a growing sense of the complexity of the humiliated, angry, vulnerable man who has always repressed the feelings that might tell him who he is. He says he won’t weep, and promptly does so. He seems incapable of love, yet the warmth he shows towards towards Sylvester McCoy’s wry, shrewd Fool always suggests otherwise. He’s haunted by the fear of madness, yet out of madness comes not only incoherent vengefulness, not only the doddering confusion that leaves him stripping to his skin, but a new-found care for others.

“Is there any cause in nature that makes these hard hearts,” McKellen’s Lear cries as he imaginatively puts his daughters on trial. And it’s a big, anguished, eloquent message from his own heart that’s directed not only at Goneril and Regan but at a planet where, as he later declares from within some weird private world only he can see, hypocritical beadles lust after the whores they are lashing, judges steal and politicians lie.

Monica Dolan’s Regan is the neurotic, obviously dangerous sister, dancing with glee as William Gaunt’s kindly Gloucester is blinded, and Barber’s Goneril the subtler one: a woman whose attempts to be reasonable and loving come across as forced and smarmy and whose inner rage, once liberated, knows no bounds.

You can see why Lear’s knights, a crazed Cossack mob, upset her. You can also believe that, in Nunn’s main innovation, she can send her servants to give graphic truth to Lear’s much discussed line, “and my poor fool is hanged”. Here, it doesn't refer to Romola Garai’s sturdy Cordelia, but to McCoy himself, who is strung up on stage.

Behind him Christopher Oram’s set, the gracefully arced and draped dress circle of a traditional theatre, gradually collapses, like British civilisation itself. And so does McKellen, intoning “never” over Cordelia’s corpse like an old, muffled church bell: a hauntingly painful ending to one of his finest performances.

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