The year 1827 started in a more promising way for Aldridge and Margaret, his wife. They had moved north so he could take advantage of opportunities offered in some of the larger cities and towns in Yorkshire, Lancashire, Durham, and Northumberland. In January he performed in Sheffield and Halifax, in February in Manchester, and in March in Sunderland and Newcastle upon Tyne. In late March and early April he made his first foray into Scotland, appearing at the Theatres Royal in Glasgow and Edinburgh. He enacted his usual characters—Othello, Oroonoko, Gambia, Hassan (in The Castle Spectre), and Mungo—but also added two new roles that were to remain in his repertoire for many years to come. In addition, he started singing regularly on stage.

The songs he sang were included in the play that became one of his greatest hits—namely, Isaac Bickerstaff's popular farce The Padlock. In this “comic opera” Aldridge played Mungo, a black servant who spoke in a West Indian dialect resembling a form of pidgin English. The play had originally been staged at Drury Lane in 1768–69 with Charles Dibdin, who had composed the music, eventually taking on the role of Mungo, which he played very successfully in blackface. “The Padlock was so well received that it was produced 54 times at Drury Lane during the 1768–1769 season,” and “of the 401 separate works (both first pieces and afterpieces) mounted [by David Garrick] at Drury Lane between 1747 and 1776, The Padlock ranks ninth in total number of performances, having been presented 142 times in eight seasons.” Mungo quickly became a stock comic figure and a popular obsession, celebrated in prints, silver tea caddies, and masquerades. Words from some of Mungo's songs entered into common discourse and were even quoted in Parliamentary debates. Aldridge was tapping into a rich vein of racial humor by playing such a familiar black character, one credited with having signaled a radical transformation in the image of blacks in British drama.