The Exorcist’s origins don’t necessarily rely on the faith of huge numbers, nor does it really matter. Based on a ‘real life’ case (that old chestnut) about a boy possessed and subsequently saved by two priests in 1949 Missouri, it was later turned into William Peter Blatty’s New York Times bestselling novel and two years later, the infamous 1973 film. The consequences of watching The Exorcist are hardly believable today in the highly desensitised culture we have had built for us. Audiences vomited or fainted; some wanted to leave the cinema but were too petrified to do so. Screenings were banned. The story’s origins are not completely relevant when such a state of elaborate fascination and disgust trail what it was to become. Did it matter if it was based on truth? Perhaps, but clever marketing always goes down a treat and this, combined with The Exorcist’s simplicity shows why it really has stood the test of time and is so damn terrifying over four decades later.

The story? There’s not much to it really: a unicorn called Penelope makes friends with a gaggle of swans and they have loads of fun gossiping about the neighbouring gold, sparkly bears. Vomit inducing. We’ve seen the possession of children especially, in many films since this one and sometimes they’re decent but often they include and rely on jump scares to make audiences feel anything or create any faeces. The Exorcist is all about tension and the horror that lies in our subconscious and the psychologies of culture and society. It battles against stigma, against perversions and against taboo. The story wants us to feel extremely uncomfortable and especially to its adaptation to the stage. Does it work? Yes and no.

Immediately before the show starts we are plunged into darkness, readying for the sickening horror that is to grab hold or perhaps to hide those lurking around the auditorium, pouncing on unsuspecting members of the audience. The overall aesthetics of The Exorcist are brilliant but I do wish it would make its mind up as to what sort of horror it intends to inflict. Are we to be sensory or mind violated? Anna Fleischle’s set looks exactly as it should: a creepy, recess ridden, old house. The action flashes from room to room, and Philip Gladwell’s eerie lighting work contributes hugely to the speedy switchover of scenes. Smells too are incredibly effective but hardly imaginative.

The ‘in your face’ horror that Sean Mathias’s production clearly wants us to experience, feels too explained… It doesn’t feel like the audience are allowed to mull it over and process. Jon Driscoll and Gemma Carrington’s projection work here is impressive, but not for a show such as this. I feel cheated and a little bit patronised that they think it necessary for a huge projection of a demon to be thrown around. Is the demon crafted in my imagination not enough? Generally, the tone is off. There are too many comedic elements (Ian McKellen as the voice of the demon is ridiculous) and I left at the end, probably due to this inconsistency, feeling very little for an experience that definitely set out to do more.

Clare Louise Connolly’s Regan is excellent at channelling both pre-pubescent child and possessed weirdo, with Tristram Wymark also impressing as the lovable and ill-fated Burke. The rest of the cast are fine and there’s only so much pouting and skulking one can endure from Adam Garcia.

The psychology of the story and this show’s treatment of it are the biggest draws. Child abuse, one of the greatest taboos for many of us, is the most horrifying issue here. We see it supernaturally and we can be forgiven for forgetting the possessed, with all her exclamations, as a child. It is prior to this, when Regan is first violated and we see she is an innocent; that is where the diabolical truly lies.

The Exorcist is playing at the Phoenix Theatre until 2018.

Photo: Robert Day