Sellotape Sisters, playing this week at the Tristan Bates Theatre in Covent Garden, gets off to an inauspicious start. Ethel and Phyllis, played by Charlotte Weston and Kellie Batchelor, are in the dressing room before performing the last episode of low rent soap opera Sellotape Sisters. Weston and Batchelor exchange some semblance of witty repartee, but, not helped by a rather echoey space, it feels a little forced and rehearsed; reaching for Ab Fab but not quite managing it.

Their co-star, Jonny Freeman as Rupert de Menthe, joins them and sets up the play’s conceit: the final episode is to not only provide resolution for the on screen drama, but will make a series of revelations about the cast’s personal lives. The ensuing plotting and scheming at times feels laboured and overdone, and at others too rushed, as if the cast are tripping over their words in an attempt to get them out. At the close of the first act the production is entertaining enough, if not exactly riveting.

The second act, however, presents a section from the soap opera itself and feels like a completely different show. The farcical, bumbling comedy of Sellotape Sisters– think Acorn Antiques meets Downtown Abbey- is uproariously funny. The pitch-perfect writing and the flawless comic timing of the cast come into their own here. It is also pleasingly intricate, like a choreographed routine, as the crossed purposes and motives of the cast and writers are drawn out. There are some excellent visual jokes and some punchy one liners that has the audience in fits of giggles.

The third act, though, feels like a step backwards. It foregrounds the work’s more serious point: that of the shifting nature of social mores and the cruelty that those who fall outside them suffer. The show makes an affecting, if slightly schmaltzy, point about the importance of social and self-acceptance, but its comic and serious elements somehow don’t quite marry.

In the end it is a little difficult to know how to take this show. It is one part a hare-brained farce, with some excellent writing and performances, and one part social commentary on our attitudes to sexual orientation over the past fifty years, from which it is tempting to draw parallels and extricate moral lessons. It is at times touching, often hilarious, but at others a tad clichéd, sententious, even. But I left the theatre smiling- perhaps I don’t need to read into it any more than that?

Sellotape Sisters is playing at the Tristan Bates Theatre until 20 August. For more information and tickets, see the Tristan Bates theatre website.