Sometimes it’s the little things that make a show, like a party bag on arrival or the splendour of an old wooden lecture theatre. Sometimes it’s the big things, like a show that fiercely tackles big pharma’s hypocrisies and underhand methods. Shit Theatre’s Guinea Pigs On Trial has the big and the little, the silly and the profound. The duo, Becca and Louise are friendly and accessible without ever losing sight of what they want to say.

During research for their last show, Job Seekers Anonymous, Becca and Louise noticed that the Job Centre was advertising paid phase one medical trials alongside or instead of employment. They decided to try and enrol. Being ushered into a space called ‘the dissection room’ seems appropriate for a show about medical trials. The two performers, inspired by the onstage persona and look of performance artist Taylor Mac, are in pyjamas and dressing gown, their faces are painted white with little black button noses – sort of like guinea pigs. Before the show proper begins they ask the audience to agree to the terms of a consent form, shouting ‘I consent’ after each line. Then they shred the form.

Shit Theatre has found the formula for the best kind of satire, the kind that makes you go “ha ha ha! Oh shit that’s actually true, that’s actually the world we live in”. They swoop vertiginously from silly jokes, like laughing at the word ‘buttock’, to pin-sharp attacks on the medical trial system. Government guidelines state that payment for a trial should not be high enough to make it an incentive to enrol but, as Becca and Louise point out, who is more likely to sign up to £3,000 for a couple of weeks’ work? Someone with money and a well paid job? Or someone unemployed?

The X Files is a running theme, the duo adopting the roles of Mulder and Scully investigating the shadowy operations of drugs trials. But when they show the opening titles to the show, they redub it with the music from Carla Lane’s Butterflies “because it works so well”. Don’t worry, all is explained in the show.

And like Butterflies, this is ostensibly a comedy but one that is digging at something deeper. Guinea Pigs On Trial is a clever show, Becca and Louise are excellent, natural performers and they are exposing the inner workings of an area most people know very little about. It would be pretty depressing if it weren’t so funny. Actually, it is pretty depressing too.