On 16 August 1819 tens of thousands of working men and women demonstrated at a place known as St Peter’s Field in Manchester, demanding reform and the repeal of the Corn Laws. The yeomanry and then hussars were ordered to attack, killing eighteen people and injuring more than four hundred. With the recent memory of the Battle of Waterloo, this slaughter went down in history as Peterloo. Shelley reacted with one of the earliest works of socialist literature, his famous ballad “The Mask of Anarchy.” This month we mark the 200th anniversary of those events and of Shelley’s great poem.