Babushka: A Sketch Show takes its name from Russian nesting dolls, which also serve as inspiration for the high-concept framing. Each sketch exists inside the previous routine, taking us further and further down the rabbit hole and promising a fascinating thread to run through their routine.

Footlights scions Mark Bittlestone, Declan Amphlett and Haydn Jenkins are behind this Inception-style sketch narrative (Sketchception? Insketchion?) They present well as a trio; to extend their own reference to the Spice Girls, they come across as a sort of melange of Sporty Spice, Nerdy Spice and Weird Spice. With previous shows acclaimed in both Cambridge and Edinburgh, they have the pedigree for comic invention that suggests we’re in for something exciting.

Ultimately though, I don't think they land the nesting device as well as they might have. Early on, a sketch where we see table football players getting the hairdryer treatment from their manager segues nicely into a pub scene above the table-football apparatus, and the occasional transition like that one does do justice to the concept. But how we got there in the first place felt forced, and the ties get gradually weaker as things go on.

Still, it's an admirable effort, and there's plenty to enjoy even if the Babushka conceit doesn’t quite work for you. Some of the best routines see them playing exaggerated versions of themselves, and they cleverly switch around which of them acts the straight man and which are the dunces. An extended fourth-wall breaking sequence about flyering techniques is a particular highlight, and a late attempt at explaining the rules of improv comedy plays in a similar space.

There were a few times when the maxim ‘less is more’ would have helped, through slightly more restrained delivery or writing. And in closing, they contrived to loop back self-referentially to one of their best early sketches – but then crowded it out with a reference to a throwaway punchline, which was lost in the middle of the show the first time round, and didn’t feel that it had earned its place as the last hurrah.

Babushka stands out in a crowded marketplace as an innovative take on a regular Fringe format – and if it tends to lapse back into familiar territory, then it’s still a strong example of the form. But I’d have liked to see something just a little tighter, which lives up more whole-heartedly to idea behind it. In the end, it’s not quite as clever as it wants to be, but it’s a good laugh all the same.