The Signalman is based on a short story Charles Dickens published in 1866 and it has been cleverly adapted by Martin Malcolm for the stage. The mediated monologue of the narrator in the original story is substituted for a first-hand account from the Signalman (Tim Larkfield) himself. He mans an isolated rail signal situated next to a deep tunnel, an eerie place where the wind whistles through, and which has already been the site of two accidents. ‘The dead’, he tells Joe the crossing sweeper (Helen Baranova), ‘were brought in here to be laid out’, and so even his office, which by rights should be cosy, is no longer his sanctuary.

Joe is a character imported from Dicken’s novel Bleak House, and here the character works as a helpless counterpoint to the Signalman, a wordless companion who bears witness to his increasingly strange behaviour. Joe’s reactions to the Signalman and his own feelings are exquisitely expressive, and yet because of the lowliness of his position he is powerless to do anything. Tim Larkfield carries the play, gradually spiralling down towards something the audience senses is horrible, and the cast do a terrific job of slowly ratcheting the unease. If A Christmas Carol is the bright, prosperous side of the Victorian Christmas, the Signalman reminds us of an alternative, but equally valid shadow side of the jollity.

At the Old Red Lion Theatre, Islington until 4 January 2020.