Interstingly enough, I've just read 'Kipling Sahib' a biography of Kipling' time[s] in India, fascinating. Concerning his knowledge, or otherwise, of 'folk' song, there is a statement that one of his relatives, an aunt I think, sang lot's of folk songs, one of which was 'False Knight on the road'. Which the author states that Kipling, on what hard evidence is not clear, used the form for 'Danny Deever', which of course PB put to Derwentwaters farewell, though it can of course be sung to several other tunes. The first part of the verse does, more or less fit False Knight on the road' but the second half doesn't.