Mary Humphreys is responsible for putting these verses together, and for the information that rue was regarded, certainly in the 19th century, as an abortifacient. Tom Bliss adapted Mary's version and recorded it on his CD Mixed Moss, adding that in the days before bird migration was properly understood swallows were believed to be immortal. Trio Threlfall on their latest CD, Sweet Nightingale, have used the same sources and come up with a slightly different version again. But which ever way you take it it's a very good and attractive song.