This is supposed to be improv, but it’s an insult to the concept.

Two mates indulgently mucking about, the only joke being how ill-prepared they are, and how bad they are at this sort of thing, is a waste of everyone’s time.

Creator Gareth Morinan not only should know better, but does. He’s aware the show’s been a dud, apologises profusely, and afterwards says he wished I’d come at the weekend, as it’d be better then – though evidence of that is sparse. I think ‘show’ is rather overstating this fiasco, though.

The premise is reasonable enough. Realising that writing an actual play as too much like hard work he’s sketched out an outline, leaving the actual scenes to be made up on the fly - even if the structure is complicated by the fact it’s a time-travelling epic.

In the hands of skilled improvisers there’s no reason why this shouldn’t work. But neither Morinan of today’s guest, Sophie Pelham, shows any sign of this. It is absolutely no exaggeration to say that they can’t commit to a character even for a sentence. As soon as they start speaking, it’s to say they don’t really know what’s going on, or to point out how bad their accents are. Nothing wrong with a bit of comic deconstruction, but something has to be constructed first.

Grab two random people off the street and they would do a better job. Again, no hyperbole… the two punters brought up on stage to flesh out the cast easily outshone both Morinan and Pelham, just by sticking to the idea that leapt into their head when put on the spot, however weak, not immediately undermining it.

‘The ambition exceeds the delivery,’ confesses Morinan in a rare moment of lucidity among all the ‘umming’ and ‘aaahing’ and ‘what happens now is, erm, basically…’ flailing – and that seems like an understatement.

If you’re a festival virgin, don’t, whatever you do, think all improv, or all free-entry show, are like this. Time-traveling? I’ve certainly lost 45 minutes.

• Morinan wrote a Correspondence piece about Chortle coming to the show unexpectedly.