“The Statute of Labourers (1351) made it illegal for peasants to accept wages that were higher than pre-plague levels. Meanwhile, food prices skyrocketed, as we should expect from a doubling of the supply of money relative to food supply. The poor, forced to endure hunger and shortages, could see ever more clearly that the source of their suffering was not just bad weather or pestilence; it was a political class growing rich from peasant labor. And if the Black Death had destroyed the survivors’ belief in the security of an unchanging life, it also led them to question the supporting ideology of feudalism. An oppressed people with a clear enemy and a belief in the reality of change is a recipe for revolution.”
http://www.fee.org/the_freeman/detail/class-war-in-the-time-of-robin-hood