Small clarification: while it was definitely rioters who ranged around St.Giles, on the extant recordings, it certainly sounds like Tim Hart sings "paupers". This is historically inaccurate, as the riots that started at St. Giles certainly did not involve only the poor, but extended throughout Scottish society.

The song is filled with indirection, however, so Tim may have meant to sing "paupers" as a clever reference to Saint Giles, who was the patron saint of paupers. He may have used "paupers" as a synecdoche for the St.Giles congregation as a whole, and possibly as a veiled reference to the economic disparity between Calvinism and the Catholic Church.