When I told a friend that I was going to see Noel and Gertie, he seemed surprised that it was being revived as it was very much aimed at audience members of a certain age when he saw it in the 1980s. There can’t be many people today who remember Gertrude Lawrence’s stage appearances first-hand; she never became a film star and died in 1953, shortly after creating the role of Anna in The King and I. Noel Coward outlived her by 20 years and his most popular plays are still frequently revived, but he’s possibly best known for achieving mythical status alongside Lawrence as symbols of a bygone age of gilded glamour. The first musical staged at central London fringe venue the Cockpit in many years, it’s a gently affecting testament to friendship respectfully directed by the ubiquitous Thom Southerland.

With a script by the late Sheridan Morley (biographer of Coward and Lawrence) comprising Coward’s songs, excerpts from his plays, and personal letters and telegrams in the style of the revues that he was renowned for, the show takes place through a wistful haze of memory and sheet music after Lawrence’s death, framed by their greatest success together, Private Lives. While Elyot and Amanda’s love brings out the worst in each other, the disciplined Coward’s influence on the capricious Lawrence was one of the most constant aspects in their lives. Morley is rather coy about Coward’s sexuality; he admits not to liking women in ‘that’ way, but regarded them as the most exciting part of theatre. Despite their real-life relationship being entirely platonic, it seems that conveying a sexual chemistry was crucial to their onstage allure.

The leads don’t quite sizzle together: Ben Stock plays the piano well, but is too boyish to convince as a jaded, middle-aged Coward. Helena Blackman (the most talented How Do You Solve a Problem Like Maria? contestant), a much better singer than the real Lawrence, is every inch the 1920s starlet with her elegant composure, a touch of haughtiness and humble origins that weren’t quite as humble as she liked to make out. Their “tremendous transatlantic bickering” via telegrams could do with more zing, and the scene from Still Life (filmed as Brief Encounter) doesn’t wholly convince, but their moments together at the piano are lovely, with Blackman’s renditions of ‘Sail Away’ and ‘Why Must the Show Go On?’ showing remarkable control and empathy.

Biographical plays ought to give an insight into the real people behind the myth. Morley’s script offers human, if idealised, portraits of two people who lived for the theatre –  when it came to balancing nine plays in Tonight at 8:30, “the strain didn’t bear thinking about; so we didn’t”.

Noel and Gertie is playing at the Cockpit Theatre until 22nd October. For more information and tickets, see the Cockpit Theatre website.