Even before a word had been spoken I knew how I was supposed to feel about ‘Chav’ Carla. High tight pony tail – check, hoodie – check, bum-bag – check, lighting up while pregnant – BINGO!

Carla and Heather went to school together. Heather (Selina Giles) is middle class and Carla (Lisa Gorgin) working class. Once friends, they fell out spectacularly during their school days with long term repercussions.

The Wasp is a play better plotted than it is written. The storyline kept me gripped and the acting was impressive, but the characterisation was far too broad and likely to fall into lazy stereotypes. Both lead actresses handled the material they were given well. I was especially impressed by Giles as Heather. Her tendency to fall into an approximation of Carla’s accent when she was bonding with her was something I – as a middle-class girl who grew up in inner London – recognised as a subtly interesting character tic.

The first half was tighter than the second. Due to a plot twist, Giles carries the latter half largely on her own against a largely silent Carla. During this Heather reveals the backstory to the women’s relationship to us. Again, while the tale itself is gripping and the delivery excellent, the actual words tended too much to melodrama. I found myself recalling my own treatment at the hands of school bullies and wondering if that would ever really have been enough to turn me – or anyone – into Heather.

Just as the costumes were a touch clunky and obvious, so too was some of the set. At one point, there is a long allusion to “the butterfly effect”. Just in case we missed it, there are not one or two but sixteen butterflies pinned to the wall of the set and lit up for good measure. It was all just a little too unsubtle.

The Wasp was entertaining, but I’m not sure it knows quite what it wants to be. As such it falls between two stalls never quite having the confidence to commit to either. Is it a racy thriller or a treatise on the effects of violence and class on upbringing? I’m not sure, and I’m not convinced the writer is either.

The Wasp is on until 12 August https://www.eticketing.co.uk/jermynstreettheatre/list.aspx?tagref=133