So, which moment from the classic 1973 film is it appropriate to quote here? Does the power of Christ compel you to see this stage adaptation? Or does it, conversely, suck [redacted]? Well, neither, very much. Those who had been anticipating a train wreck or a so-bad-it’s-good version will be disappointed, but so will those wanting to be scared out of their little cotton socks.

John Pielmeier’s play (which premièred in Los Angeles in 2012) works from William Peter Blatty’s novel rather than his screenplay. Consequently, for instance, the exorcism itself occupies only the final ten of this production’s 95 intervalless minutes. (And how unusual to see a stage version barely three-quarters as long as its screen cousin.) But compression has had some awkward effects. A succession of doctors remain, whilst Detective Kinderman – the viewpoint character for those readers of the novel not steeped in Catholicism – vanishes, and with him the entire plot strand of criminal investigation. The novel’s long-sustained ambiguity about what twelve-year-old Regan is actually undergoing is here blown to shreds with her very first experience (in an entirely invented scene in the attic), with the demon an external entity from the get-go. And, lovely coup though it is for director Sean Mathias to have secured the uncredited services of his former partner for the voice of the demon, doesn’t it make us rather more likely to root for such an infernal presence when it sounds like Ian McKellen?

The cast – led by Jenny Seagrove and Clare Louise Connolly as mother and daughter, Peter Bowles and Adam Garcia as old and young priests – play fairly consistent second fiddle to visual effects, most of which are simple projections but which can be disproportionately effective (as when Regan’s face morphs into that of the dead mother of doubting Father Karras). Anna Fleischle’s design and Philip Gladwell’s lighting make much use of total blackout (with even exit signs in the auditorium extinguished) and lightning flashes when shifting the action between the several discrete playing areas on two levels. It all does a perfectly good job of telling the story, though not of giving you the screaming heebie-jeebies. There’s no overwhelming need to spider-walk to the box office.

Written for the Financial Times.