Even on his 17th visit to the Fringe, the sublime Stewart Lee is one of the most intelligent, skilful and original comic voices on offer. But even so, he’s not quite as funny as a fart. That the expulsion of waste gas is the most hilarious thing imaginable is just one of the many theses he painstakingly explains in this comedy masterclass. It sounds a puerile subject, but Lee’s technique is to treat it with such a considered, measured gravity you trick yourself into thinking it must be serious and important, even when he suggests farting as a solution to world peace.

The gap between this elevated approach and the juvenile subject is where the comedy lies, especially when he punctures his own thoughtful solemnity at the routine’s end. Not that it’s just the wonderful lines that get a laugh, the languid pauses and quiet build-ups build such anticipation that you’re suppressing chuckles before the punchline even arrives. Lee is nothing if not a superlative technician, yet original enough to follow his own comic blueprint rather that reaching for the universal ploys found in the pages of teach-yourself stand-up manuals. In fact, when he does feel the need to employ, say, the rule of three (that being the optimum number of items in any list for most impact ­ eg, ‘an Englishman, an Irishman and a Scotsman’, or ‘ein volk, ein Reich, ein Fuhrer’), he knowingly deconstructs and subverts the idea, keeping the audience in on the joke.

Another example is that 9/11 to Britons should mean November 9 ­ an observation made by many a comic in the three years the date became significant. Yet Lee mentions it so relentlessly that we are beaten into submission by the very repetition more than the actual gag itself. Exaggerating to comic effect is another staple, but Lee takes even that to such ridiculous extremes that it becomes a rich, unique pleasure. He has fairly strong views on most aspects of comedy’s structure and execution, as demonstrated by the ridiculously funny overanalysis of a pun he made to film director Ang Lee, who misunderstood the entire concept of wordplay and thus sparked a huge row laced with accusations of racism.

That subject is hinted at again when Lee launches a savage, unrestrained broadside at the Scottish, belittling their nation, beliefs and heroes in a deliberate wind-up. But this low-level racism is perfectly acceptable, he ironically claims, since he’s ‘Scotch’ himself ­ at least by birth if not upbringing. Ethnic comics everywhere should take note of the sarcasm. Not that he’s shy about naming and shaming who he considers comedy’s worst practitioners, likening Graham Norton to ‘a pink jackboot stomping on a human face for all eternity’ but reserving his most vitriolic scorn for Ben Elton, who he considers slightly less popular than Osama Bin Laden, because at least the terrorist mastermind lived his life according to a strict moral code.

Lee has something in common with Elton, of course, having once been at the vanguard of a stand-up movement and now the writer of a West End show. But that’s where the similarities, thankfully, end, with Lee still on top of his game, and true to his original voice. Anyone serious about comedy should watch and learn.