Before about 1850, there were many bawdy songs in English printed in small songbooks and on ballad sheets - some of them quite explicit if expressed in metaphor. However, only a few survived in oral tradition following a wave of puritanism that affected both the Catholic and Protestant religious traditions.

The song about the 'ancient old Irish french letter' is quite recent, from a formally educated tradition, and concerns Brian Boru and his wife. It can be easily found by a Google search - the first line is "I was up to me oxters (or uxters) in muck, sir,"