He may not be a household name but, 50 years after his death, Harry Beck still helps millions of people find their way home – and all around London, too. The tortuous creation of the diagrammatic tube map, first conceived by Beck in 1931, is the subject of Andy Burden’s fond bio-drama staged in London Transport Museum’s Cubic theatre, where the seats are upholstered in a moquette familiar from the tube. As played by Simon Snashall, Beck is a pun-loving, Pooterish figure in spectacles and sweater vest. He is introduced in his retirement in the New Forest, where he and his wife, Nora (Ashley Christmas), tell their story over cups of tea. It is presented as very much a joint effort as Nora advocates a sense of “graphic grace” and colour in the design and encourages Harry to elucidate the interchanges between lines when he endeavours to represent the chaotic spaghetti network of London Underground, previously depicted sprawling overground on a topographical map of the capital. Instead of showing the realistic distance between each station, Beck settles on a comprehensible design inspired by his work as an apprentice draughtsman on electrical circuit diagrams. The complexity of the task is cleverly demonstrated by some business involving colourful ribbons, representing each line, tied around the furniture on Sue Condie’s domestic set, with someone in the front row momentarily becoming Kennington station. A handful of sketches are done at Harry’s drawing board but Burden’s production for the Natural Theatre Company could do more to visually celebrate his work. In general, the script often tells rather than shows, its evident research relayed as lesson rather than drama. But the splendour of the former London Transport office at 55 Broadway, a Grade I-listed building by St James’s Park, is described evocatively and Burden deftly suggests how the premises themselves also inspired the diagram. A reference to the now disused York Road station helps convey the changing face of London itself, not just the Tube map. The personal and professional are continually entwined, partly because Beck’s work was largely done at home as a hobby and hardly remunerated. As Nora and Harry walk us through their lives, he bashfully tries to skim over any intimate stuff. Anyway, their romance is always overshadowed by his obsession – witness their Valentine’s Day trip to observe Finchley station. The couple’s inability to have children is handled delicately, though their later marital struggles lack pungency, as does Harry’s bitterness at his superiors first for deeming his work too radical and then for not giving him enough credit. Today, he is recognised in an inscription on the Tube maps, though he always preferred to call them diagrams. Burden largely follows Beck’s own design principles, creating a work that is unfussy and direct. If the play’s flaws would perhaps be more exposed on a larger stage, it makes an agreeable accompaniment to some of the history depicted upstairs at the museum. Part of the triumph of Beck’s diagram is that it can still be adapted for changes in the transport network; there is enough compelling material in this hour-long drama, too, for it to evolve in the future. At Cubic theatre, London Transport Museum, until 10 November