I think it's selections from the ten (twelve?)-volume set THE LONG HARVEST,on Argo, and now out of print. See this site for the full list of songs. (I still can't make those blue linky things.)
http://folkcatalogue.wordpress.com/2009/05/22/1967-ewan-maccoll-peggy-seeger-the-long-harvest-vols-1-4/