I know; a lot of you disagree with me. You thought the Manics should be at number 1. Personally, I'm put off a bit by their constant use of the f-word, which has made my job in finding a good live version of one of their songs difficult.
This song has the catchy short title "If you tolerate this your children will be next".
It is a highly intelligent song, based on the exodus of Welsh volunteers to the International Brigade in the late 1930s, to fight on the ill-fated losing side in the Spanish Civil War. As a lesson in cultural history, it cannot be bettered.