There are a lot of sources for this episode. I used a lot of general background material on the period, and on the British Military that I’d used for the Napoleonic Episodes and Mt Tambora

Specific sources for the Peterloo episode were

• “Hand Weavers Lament” (Traditional/Popular song)
• Artists Print “The Manchester Reform Meeting Dispersed by Civilian and Military Power.” from August 1819
• HONE, WILLIAM “The Political House that Jack Built”
• Simon Schama’s History of England vol2
• https://www.theguardian.com/news/2018/jan/04/peterloo-massacre-bloody-clash-that-changed-britain
• https://www.theguardian.com/commentisfree/2018/oct/29/peterloo-britain-kings-queens-mike-leigh-massacre
• E.P. Thompson The making of the working class
• MESSINGER, G: “Manchester in the Victorian Age – The Half Known City”
• Riding, J; “Peterloo, the story of the massacre”
• Walker, A. Stanley. “Peterloo, Shelley and Reform.” PMLA, vol. 40, no. 1, 1925, pp. 128–164.
• POOLE, ROBERT. “’By the Law or the Sword’: Peterloo Revisited.” History, vol. 91, no. 2 (302), 2006, pp. 254–276
• POOLE, ROBERT; “The Manchester Observer: biography of a radical
  newspaper” http://clok.uclan.ac.uk/28037/1/28037.pdf
• https://revjosephharrison.wordpress.com/the-peterloo-era-1819/ (A good article with plenty of primary source letters quoted).
• http://britishcavalryregiments.com/35-15H/15H.html
• https://www.nam.ac.uk/explore/15th-kings-hussars
• https://london-medals.co.uk/the-exceptional-and-important-peninsular-war-southern-france-1814-orthes-and-toulouse-well-documented-waterloo-1815-and-possible-peterloo-massacre-officer-s-pair-awarded-to-lieutenant-later-colonel-henry-lane-15th-king-s-regiment-of-hussars-later-1st
• Report of the Metropolitan and Central Committee, appointed for the relief of the Manchester sufferers; with an appendix, containing the names of the sufferers, and the nature and extent of their injuries. (https://www.bl.uk/collection-items/lists-of-the-killed-and-wounded-from-the-peterloo-massacre)
• http://historyofpublicspace.uk/peterloo/
• http://www.peterloomassacre.org/names.html This is the spreadsheet with the complete list of the victims, occupations, age/sex, and cause of death. It is a fantastic source.