With this spectacular return to form, Pappy’s have set the bar for sketch comedy this Fringe. This is a beautifully constructed pyramid of lunacy in which physical and verbal gags fly around at a dizzying pace, maintaining a constant level of laughs that occasionally explode into almost uncontrollable guffaws when a perfectly-timed line of exquisite power hits home.

They perform a script that doesn’t Have a Word out of place, with such genuine gusto and lightness of touch that the Queen Dome is soon fizzing with a shared enthusiasm. They have great chemistry and not a jot of cynicism in their bones. They might occasionally trade insults with each other, even slipping the naughtiest words past the censor, but its done with an infectious joie de vivre.

The writing is a joy. Even scenes that merely seem ‘pretty good’ when you first encounter are subsequently revealed to have a pivotal role in this multi-layered story. The premise is that Matthew Crosby, Tom Parry and Ben Clark are in their dotage, revisiting the venue where they performed their last ever show. But their memories are fading, and they can’t quite figure out what it was that pulled them apart, so they piece together the night sketch by brilliant sketch.

You may know this trio used to be a quartet, and here they have really found the perfect vehicle for their new set-up. Comedy is built on rules of three, after all, and here they reinvent the centuries-old ‘set-up, reinforce, subvert’ format to ‘set-up, subvert and subvert again’. That way you get 50 per cent more laughs.

The narrative builds up pace to match the performance as we are introduced to recurring ideas, such as the real relationship between the friends of Dorothy  in the Wizard Of Oz, a Britain’s Got Factor style talent show that gets stuck in a paradoxical loop, and a serios of transmogrifying holy men, in what provides the most deliciously politically incorrect moment of the festival, which could nonetheless  only offend the most preposterously touchy.

You see there’s something incredibly endearing about this lovable trio that makes everything all right. Normally the appearance of a dildo on stage is the last act of the desperate, here it’s an integral part of the fun. And how they can maintain their – and the audience’s – levels of energy for the full hour is a mystery, since it’s a secret that eludes even some of the best comics.

Callbacks abound, subtly showing the Knockabout silliness is underpinned by incredibly sharp minds, appeasing both the head and the heart. If this doesn’t put a broad grin on your face, you might be malfunctioning in one or the other.