You do not expect a fight at a Ron Sexsmith show. Yet toward the end of this gig, during the opening bars of the self-effacing shuffle Get in Line, a proper rammy breaks out, with the disruptive patrons eventually being ejected. Sexsmith and his rootsy four-piece continue playing throughout, like the world’s most dapper and lovesick roadhouse bar band.

Perhaps it was a debate about just how overlooked Sexsmith is that escalated. His passionate fans, both civilians and celebrities such as Elvis Costello and Chris Martin, are deeply protective of the Canadian singer-songwriter and his knack for fusing the melodic and melancholic. They can also be pretty prickly when it comes to his perceived lack of commercial success.

It doesn’t seem to bother Sexsmith, who performs in a dark suit jacket daubed with a bright maple leaf and introduces highlights of his enviable back catalogue with warmth and wit. In 2015, he’s celebrating two decades of a recording career that started at the relatively late age of 30. His recent 14th album, Carousel One, is as sweet and off-handedly beautiful as anything he’s ever written.

The new songs sound great. Getaway Car is an escapist dream rendered in irresistible bar-boogie, while Can’t Get My Act Together is a winningly upbeat celebration of perpetual dissolution. Saint Bernard, in which Sexsmith imagines furry salvation in the form of a faithful rescue hound “like a four-legged minibar”, has an additional zoological zigzag, its chorus echoing Manfred Mann’s Pretty Flamingo.

He also plays songs from his eponymous debut, taking care to point out the weird bum chord in Words We Never Use that he refused to remove despite pleas from his publisher and revisiting Secret Heart, a song that went stratospheric for Feist when she covered it. Sexsmith’s original may be more measured in tempo but it gets there, and, like the man himself, feels richer for the detours.

• At St George’s, Bristol, 29 June. Box office: 0845 40 24 001. Then touring.