In an event as large and competitive as the Fringe, it doesn’t pay to restrict your potential audience. Go for a niche, by all means, but hit it right, and be careful not to alienate curious bystanders. Unfortunately, the target market for what Rik Carranza’s doing in I’m A Fan isn’t dipping casually into the free fringe, it is hanging round the back rooms of fan conventions sniggering to itself that you didn’t spot the continuity error in season 3, episode 5.

Star Trek is Carranza’s chosen indulgence, and to question his choice of material is not to dismiss Trekkies as a breed. It’s just that Carranza ploughs deep, too deep, into that world. Forget knockabout dad-gags about final frontiers and being beamed up, this has punchlines that appear to require encyclopaedic knowledge, and might not be that funny even then. He visibly brightens when he identifies fellow travellers, of which there are a couple in today, and engages them in conversation about Trekkie arcana, not letting the presence of other audience members interrupt a discussion about favourite episodes.

But Star Trek is not all there is to this set. Carranza’s discovery, abandonment and re-adoption of the programme runs in parallel to the highs and lows in his own life story, including bullying, love and break-up. It adds another dimension, but it’s not a smooth ride. Revelations hit you like a dead weight, as if the stranger you’re passing the time of day with at the bus stop just told you their dog died. They are just hung out there with little to no comic scaffolding and appear to matter too much to be funny.

That imperviousness to audience response proves to be one of Carranza’s strengths. He’s an unflappable performer, always talking, always smiling (except when delivering those bombshells). He may have been bullied there, but he displays a boarding school self-confidence. He’s welcoming when you come in, and you’re safe from unpredictability.

In fact, if there isn’t a performance strand at the Destination Star Trek convention he raves about, they should create one. Carranza would be a hero. For non-fans, though, he offers little to cling on.