OTHELLO has been running for two weeks in Birmingham. Excellent reviews have boyed the company and the show is being very well received. Last night I could hear people crying in the audience as the play ended - with great credit due to Emilia, played by Emma Christer, who is providing a strong emotional power to the final scene.

I have never been as consumed by a part as preparing for Iago demands. The sheer amount of work required to bring it to the stage has been daunting - (it's the third biggest part Shakespeare wrote after Hamlet and Richard III) - and yet it is so beautifully written and constructed that it is not by any means the hardest or most tiring part to perform. Even though matinee/evening days mean I am speaking virtually non-stop for 4 hours, it never feels like hard work. Thank goodness again for Rudi Shelly from the Bristol Old Vic Theatre School. I could not have played this part without his instruction for three years at Bristol. Everything he taught us brings itself to bear on a part like Iago.

For anyone interested in the process of getting there, I had never dreamed of playing this part. After PROOF finished in the West End, I asked the director John Harrison what he'd like to do next. He picked OTHELLO, saying he'd always thought I should play Iago. In fifteen years of running the BSC it's only the second time I've ever been 'cast' in something (the first time was John's idea too - Hastings in She Stoops to Conquer! - one of the happiest productions of my lifetime). The only problem was that I could not see myself playing Iago at all.

My initial struggle with Iago was how it was going to be possible for me to enjoy being malicious when a malicious thought has never crossed my mind - and how such an evil man could be so charming: it is clearly essential that everyone in the play trusts Iago. Play him evil and it makes everyone around him look like idiots. Yet his behaviour is clearly heinous. How to get into this evil man's head and enjoy it?

The first clue came from a chat with Ronnie Dorsey, our resident wardrobe, who said Iago reminded her of a psychopath she knew (!) which prompted my memory of a profoundly challenging interview I'd seen three years earlier of Richard Kuklinski, a hit-man credited with two hundred murders (which you can now watch on youtube - it's the interview where he's wearing a white shirt). This supremely efficient killer, who had done the worst things to another human I have ever heard described, was a charming, personable man. It was my first clue into the true nature of the clinical psychopath and started me on the road of training my mind to think like one.

Of critical help was the work and research of Dr Robert Hare. His celebrated checklist, published in 1980, details the 20 principal characteristics of the psychopath and it is mind-blowing to appreciate that Shakespeare completely understood this syndrome some four hundred years before Hare's checklist was first published. My bible became Dr Hare's book WITHOUT CONSCIENCE and slowly it fell together. I think I now understood how the psychopath thinks! I am hoping I will forget as soon as the show is over - it's weird how the odd psychopathic thought has flashed through my mind!!

The production is in London for four days at The Bloomsbury if you can't see it in Birmingham.

Above all else, it is amazing to work with the words written by Shakespeare, whose extraordinary understanding of the human condition constantly defies belief.