There are enough books of bawdy lyrics around that someone must discuss this. The Erotic Muse, or something by Oscar Brand?

I just pulled out Cray's second edition of The Erotic Muse and on page xviii is this observation:

Prior to the sixteenth century, the word "fuck" carried no opprobrium. Sometime after 1571, when it appeared in a poem satirizing the clergy, the word fell into disrepute, to appear only in learned dictionaries and underground literature.

As early as 1300, "shit" appears in print as a verb; "piss" is equally as old. Until perhaps the middle of the eighteenth century, their use was perfectly acceptable. Up to the fifteenth century, "cunt" meant "cunt" and there was no attempt to find new euphemism or dysphemism for this anatomical feature.

Though it was considered to be correct from 1000 A.D. on, the word "breast" fell into disrepute with the Victorians, and was replaced by the more ambiguous "bosom." A hundred years later, "breast" is again in use, and "bosom" relegated to flowery valentines and women's clothing patterns.

According to Peter Fryer's Mrs. Grundy, Studies in English Prudery, the word "cock," even when it did not refer to the penis, was banned well before the Age of Queen Victoria. The male chicken was a rooster after 1772. Cockroaches became just roaches in the 1820s. Haycocks were renamed haystacks at the same time. [Sounds like Queen Victoria's reign isn't so much the source of the prudish ideas, but coincided with the prudish movement fully underway and became associated with it]

[snip] (several paragraphs describing "obscene" and skipping to pg. xix)

Not until postal inspector Anthony Comstock mounted his crusade in the 1870s did the United States Congress get around to passing laws against mailing sexually graphic matter. Paradoxically, the United States Constitution now protects those speeches and pronouncements that in defaming a particular religion were once felt to be criminally actionable.

From there, edited and redacted text of songs is discussed, and I think if you read between the lines you'll come up with a context to help establish a sort of public performance (music hall) context in which self-editing required the sly re-write of formerly openly bawdy songs.

This is of course a semi-educated guess. Cray lists a number of other collectors of these songs so you might have to visit your local music library to track down some more discussion of music censorship in the context of suppression by clergy, the mail, and the courts.

SRS