From Tony Hancock's reverence for Fred's Pie Stall and The Goodies' Ecky Thump, through The League Of Gentlemen's 'special stuff' and Tom Stade's meat van routine, all the way up to the Beef And Dairy Podcast, the mass slaughter and processing of animals for human consumption has inspired some memorable comedy.

But a whole show devoted to the Scottish indelicacy of the square, or Lorne, sausage, the casing-free slab of pocked, spongy pink served as part of a fry-up or in a morning roll? Credit to Scott Agnew, who survived a heart attack and three cardiac arrests over lockdown, for embracing his nemesis in this high-concept, hyperlocal, over-reaching nonsense.

The premise – with the audience getting a free roll and sausage – isn’t quite as foolhardy as it sounds, or as Agnew occasionally admits to in mutters and snickering asides. Scottish theatre luminary David MacLennan created the internationally adopted A Play, A Pie And A Pint concept at another Glasgow International Comedy Festival venue, Oran Mor. And the bribery helps Agnew attract a sizeable crowd for an early afternoon show in a craft brewery on one of the first sunny days of the year.

What's more, Scotland also gave the world Burns Night and the toasting of the much mythologised haggis. The routines of Tommy Lorne – the music hall comedian after whom the sausage is said to be named – may not be as revered as Robert Burns's verse, nor may he even have been a fan of the meaty delicacy. But he serves as the spiritual figurehead of Agnew's Masonic-like Square Sausage Society, with plenty of proud tradition to spoof, dating from its founding principle of opposing the hated English link sausage.

Sausagemeister Agnew tub-thumps for the square variety's superiority from behind his lectern, sporting a red beret that evokes both revolutionary sentiment and Sheena Easton's heyday as Prince's muse. The black cape is just an additional showbiz flourish, while a folder with points of order ensures that lines need not have been memorised.

Agnew claims to have junked most of the Royal Family material that was the show's backbone last-minute in the wake of the Princess of Wales's cancer announcement, retaining only a passing jibe at the King's infamous, link sausage-like fingers as evidence of the imperial yoke the Scots find themselves under.

What he offers instead, is a potted alternative history of the Lorne and its followers. It's impressively wide-ranging and imaginative, far more than it needs to be, even if clearly cobbled together from feverish Wikipedia study.

As a stand-up, the gay comic has never been shy about innuendo. But he largely eschews gratuitous meat-packing gags. Glasgow's sectarian split, the porcine-shunning beliefs of the warring factions in the Middle East and even the English-Scots divide and Caledonian independence are only lightly touched upon – or swerved altogether – as he presents a full picture of two irreconcilable cultures, separated by the shape of their bangers.

He hails the Lorne as gaining pre-eminence through the Scottish diaspora, with its influence on all-conquering American fast food. At the same time, he places it in established folk customs, leading the crowd through convincing but fictional ancient ballads with some rousing karaoke.

The interweaving of the conceit with the venerated Tommy Lorne's life and career is artfully done too. Yet the limits of the scant source material – and indeed of the show itself – become increasingly apparent. Foregrounding the shakiness of both becomes the joke for the remainder of the hour, the fragility of founding myths, the pompous bluff and insecurity of such hoodwinks. 

By the time Agnew fully throws Tommy under the bus by sharing some of his century-old routines, time having not been kind, the jig is well and truly up.

Indeed, as the Glaswegian slumps into a sofa for an extended Q&A with fellow comics Susan Riddell and Rosco McClelland about just how they prepare and consume their morning roll, the copious filler in the sausage theme has been tacitly accepted by all.

Still, it was an entertaining wheeze while it lasted. And there were some delightful touches, especially at the beginning, in the nod to Glasgow's recent Wonka Experience sham and the Love Lorne song supplied by The Sensational Alex Salmond Gastric Band, aka veteran musical comic Tommy Mackay. 

This feels like a show unlikely to be repeated, though apparently it's National Square Sausage Day today, so maybe it'll become an annual fixture. Regardless, Agnew’s show is unlikely to be forgotten by those who witnessed it.

• The Glasgow International Comedy Festival runs until Sunday.