I have a lot of songs about the Annuity Tax in 19th century Edinburgh, links and historical discussion here:

http://www.campin.me.uk/Embro/Webrelease/Embro/15kirk/15kirk.htm

There were a few (not quite as good) songs about Thatcher's Poll Tax. Maybe the best to come out of that was an instrumental tune, Sandy Mathers' reel "Repeal the Poll Tax".

How about "Raghupati Raghava Raja Ram"? See here:

http://jamesmys.blogspot.co.uk/2008/07/salt-march-march-towards-independence.html