The note in the Penguin collection is:

Benjamin Bowmaneer (JEFDSS I 97)

In folklore, the tailor seldom plays a noble part, perhaps because his profession does not call for lustihood. 'Nine tailors make a man', says the proverb, and a popular children's rhyme tells of four and twenty tailors frightened by a snail. The amusing 'Benjamin Bowmaneer' seems to perpetuate the folks' injustice to men of an honourable trade. Perhaps the song has a secondary, satirical meaning that eludes us? It has been suggested that 'Castors away' may mean 'Hats off', the castor being a slang word for a beaver hat, or by extension, any headgear. It may also mean 'Cast us away!', and thus be related to a sailor's song. The tune's resemblance to the 'Spanish Ladies' melody, much used for sea-song texts, would seem to strengthen this possibilty. We have not found a set of this song complete with tune elsewhere. [Ralph Vaughan Williams and A.L. Lloyd].

--Stewie.