Also known simply as "Blacksmith," this traditional English folk song is number 816 in the Roud Folk Song Index
. As with most such songs it has many variants, including most notably an adaptation by the composer Ralph Vaughan Williams for the hymn "To Be A Pilgrim."
The oldest version appears to be a broadside ballad printed in 1803, although the melody was collected much later. It appears that the blacksmith's hammer may be an ancient phallic symbol, which does rather detract from the romance of the song.
Alexander Baron - London, England