The basement of CoLab Factory is the perfect setting for Mechanical Thought’s immersive production set in 1941. Four main rooms – a ‘pub’ upstairs, code-cracking rooms Hut 6 and Hut 8, and an office – plus two hidden rooms do an impressive job of simulating the paper-strewn, diagram-replete, secrecy-locked Bletchley Park.
An initial 40 minutes of exposition and team cryptanalysis is a bit of a strain, feeling more classroom than theatre, but once the audience (working separately) crack the code, Illicit Signals Bletchley releases the full force of its story. Audience members are encouraged to follow performers from room to room, witnessing slices of an unfolding scandal and participating in the story in small but enjoyable ways.
The main focus of the show is Alan Turing (played with a trembling vulnerability by Edward Cartwright), the genius mathematician who led Hut 8 and was key to the cracking of the Enigma Code.
The latter half of the production revolves around the discovery, discussion and attempted concealment of his homosexuality. Nevertheless, other characters stand out, equipped with a snappy script and the opportunity to give emotionally nuanced performances: David Alwyn’s chief cryptographer Alfred ‘Dilly’ Knox twinkles with charisma and booms with drama; Tom Black is a dashing Gordon Welchman, excelling in understated dryness.
The show succeeds because of its intimacy. Large scale immersive productions like Guild of Misrule’s The Great Gatsby  – upstairs at the same venue – may have more to spend on set and costumes, but Mechanical Thought’s production has a powerful individuality and a generous, personal approach to its audience.