There is a book—

Folk Songs Collected by Ralph Vaughan Williams, edited by Roy Palmer (London: J. M. Dent, 1983)

A review says: "Roy Palmer's book contains 121 of the 800-odd folksongs which Vaughan Williams collected between 1903 and 1913. … Seventy have not hitherto been published."

Can you quote any words from the song? How did you hear of it?