No, earlier than both these. Pete Seeger says in the book of the same title: "Idris Davies, a coal miner in South Wales, was a friend of Dylan Thomas. I came across this poem reprinted in one of Thomas's essays. After the failure of the general strike of 1926, Idris Davies determined to leave coal mining. He studied nights for four years, and finally passed his examinations to Nottingham University. After graduation he became a school teacher in London and published three slim volumes of poetry. "Rhymney is a typical mining town: one hundred yards wide and two miles long..." The music to this poem is by Pete Seeger. His description of a Welsh mining town is spot on, by the way.