The Youtube version cited above appears to be from the MacColl CD "Antiquities". Some of the names differ from those posted from the Peggy Seeger songbook. The first name sounds like "Mcluhan Saagy" (?) or "Mclure and Saagy"(?), instead of "Kazim Arli". And there is "David Webster" instead of "The Birmingham Six".
BTW, the biographical link for "Kobayashi" above seems to be dead. This name possibly refers to Takiji Kobayashi (1903-1933), a Japanese communist and novelist who died after being tortured by police.
Does anybody know about Juan Hernandez? There was a Juan Hernandez Saravia who was a prominent Republican military officer during the Spanish Civil War.