The sketch duo, The Pin, first rose to prominence with a wickedly clever series of Fringe shows. They were pretty much unlike anything I’d seen in sketch comedy, endowed both with all of the formal inventiveness of the Pythons but at the same time dodging the flabbiness that the Python-esque style often indulged.

They stretched at the seams of sketch comedy, with incomplete sketches, spliced-together sketches which subverted the notion of the predictable ‘call back’ thread in comic routines, and of course, straightforwardly silly sketches that would punctuate the delicate, finely wrought clevernesses with outbreaks of joyous absurdity.

After three successful series on Radio 4, winning best comedy at the BBC radio awards in 2016, Alex Owen and Ben Ashenden return to the Fringe this year, following a brief hiatus, with ‘The Pin: Backstage’.

We are introduced to the pair as a notional warm-up act for Philip and Robin, another comedy duo waiting in the wings. So, the first half hour treads through some of The Pin’s radio material, Alex taking on an air of amiable incompetence and Ben a sort of faux-seriousness. It’s familiar Pin territory – skits with a misplaced ‘twist’, sketches which revolve around silly puns, routines that artfully fold back in on themselves – but soon Philip and Robin come on and we are left ‘backstage’ with Alex and Ben.

We hear snatches of Philip’s and Robin’s material on stage – it’s music hall comedy, reminiscent of Paul Whitehouse’s Arthur Atkinson character in the Fast Show, who tells incomprehensible jokes to gales and gales of laughter. That sparseness that was so much a hallmark of their earlier stuff and of the first portion of this show – where the comedy sits in a sort of decontextualized space, without reference to politics or other comedic traditions – is deepened into something different altogether.

And soon, the two performances begin to merge, as Robin comes on backstage (played by Ben in ridiculous Frank Spencer style) and encounters Alex, as ‘Alex from The Pin’. And vice versa – Alex, as Philip (a kind of weird, heightened version of Carry On’s Charles Hawtrey), encounters Ben in his ‘Pin’ incarnation. It’s a very sophisticated form of comedy – as we are invited to laugh at a clash of comedic personae and traditions played out at lightning speed, as Alex and Ben shift seamlessly between Philip and Robin.

Eventually, The Pin replace Philip and Robin as the main act on stage as the drama reaches a logical endpoint, playing as it does off a hilarious series of real-time iconoclastic reckonings with British comedy’s near-past. Ambitious, right? But it really works, partly because the comedy emerges in such an affectionate atmosphere, with the audience complicit in the essential conceit, both onstage and backstage, at once observing, and being observed by, Ben, Alex, Philip and Robin.

The Pin: Backstage runs until the 27th August at Pleasance Courtyard