This is from a biography of James Montgomery:

http://www.cyberhymnal.org/bio/m/o/n/montgomery_j.htm

When Montgomery was five years old, his fam­i­ly moved to the Mo­rav­i­an set­tle­ment at Grace­hill, near Bal­ly­mena, Coun­ty An­trim. Two years lat­er, he was sent to the Ful­neck Sem­in­ary in York­shire. He left Ful­neck in 1787 to work in a shop in Mir­field, near Wake­field. Soon tir­ing of that, he se­cured a sim­i­lar po­si­tion at Wath, near Rother­ham, on­ly to find it as un­suit­a­ble as his pre­vi­ous job. A trip to Lon­don, hop­ing to find a pub­lish­er for his youth­ful po­ems, end­ed in fail­ure. In 1792, he glad­ly left Wath for Shef­field to be assistant to Mr. Gales, auc­tion­eer, book­sel­ler, and print­er of the Shef­field Reg­is­ter. In 1794, Gales left Eng­land to avoid po­lit­ic­al prosecu­tion. Mont­gom­ery took the Shef­field Reg­is­ter in hand, changed its name to the Shef­field Iris, and con­tin­ued to ed­it it for 32 years. Dur­ing the next two years he was imprisoned twice, first for re­print­ing a song in com­mem­or­a­tion of the fall of the Bas­tille, then for giving an ac­count of a ri­ot in Shef­field.

That gives a fairly strong hint about who might be responsible for the name.