Below is an ABC notation of this song. It is transposed, as accurately as I can, from number 2 in a series of 24- page songbooks called "New City Songster" produced by Ewan MacColl and Peggy Seeger. This particular one is dated Sept 1969 and cost 2/6 – half a crown - (12.5p). Although the song is in 4/4 time some bars are 6/4 and the chords given here are not quite what I would use. As I say I am only transposing here, not reinterpreting.
This tune is not quite the same as that which Christy sings. I gather that Christy has some difficulties getting the hang of the original and spent some time twisting it into a shape that suited him.