The tracks with Ralph Rinzler were presumably recorded while Ralph was resident in London, which I understand was from 1957 to 1959, when he returned to New York (information from Richard Gagne, "Ralph Rinzler, Folklorist: Professional Biography". Available on the web via Google Search. He was mainly occupied in accompanying Dominic Behan, A.L. Lloyd and Ewan MacColl according to that source, before returning to the U.S. where he started the Greenbriar Boys.