Samuel Plimsoll was an advocate for better working conditions for sailors, and for a lot of other things. A lot of contemporary accounts refer to him as an agitator.

Research:

• Bibby, Miriam. “Samuel Plimsoll and the Plimsoll Line.” Historic UK. June 14, 2024. https://www.historic-uk.com/HistoryUK/HistoryofBritain/Samuel-Plimsoll-Line/
• Britannica Editors. "Samuel Plimsoll". Encyclopedia Britannica, 30 May. 2026, https://www.britannica.com/biography/Samuel-Plimsoll
• “Death of Mr. Samuel Plimsoll.” The Lichfield Mercury. June 4, 1898. https://www.newspapers.com/image/797510210/?match=1&terms=%22samuel%20plimsoll%22
• “Friends of Humanity.” Democrat and Chronicle. Apr 27, 1913. https://www.newspapers.com/image/135735684/?match=1&terms=%22samuel%20plimsoll%22
• Glover, William. “Samuel Plimsoll and the 1880 Carriage of Grain Legislation.” The Northern Mariner / Le marin du nord, XXX, No. 4 (Winter 2020), 419-448. https://www.cnrs-scrn.org/northern_mariner/vol30/tnm_30_419-448.pdf
• “Jack Tar’s Friend.” The Atchison Daily Globe. July 17, 1896. https://www.newspapers.com/image/479999267/?match=4&terms=%22samuel%20plimsoll%22
• Japp, Alexander H. “Good men and true : biographies of workers in the fields of beneficence and benevolence.” Philadelphia. Gebbie. 1890. Accessed online: https://archive.org/details/goodmentrue0000unse/page/10/mode/2up
• Jones, Nicolette. “The Plimsoll Sensation.” London. Little, Brown. 2006.
• Langenberg, William H. “The Plimsoll Mark.” U.S. Naval Institute. Naval History. June 1992. https://www.usni.org/magazines/naval-history-magazine/1992/june/plimsoll-mark
• “Lundhill Colliery Explosion.” Northern Mine Research Society. https://nmrs.org.uk/mines-map/accidents-disasters/yorkshire/lundhill-colliery-explosion-barnsley-1857/
• “The Name of Samuel Plimsoll … “ Birmingham Gazette. June 4, 1898. https://www.newspapers.com/image/815489724/?match=1&terms=%22samuel%20plimsoll%22
• “People's College Sheffield (1842 - 1878).” University of Sheffield. https://archives.shef.ac.uk/agents/corporate_entities/212
• Plimsoll, Samuel. “Our Seamen: An Appeal.” London. Virtue. 1873. Accessed online: https://archive.org/details/b20406691/page/n15/mode/2up
• Robertson, Jen. “It's Plimsoll Day! (and we're talking about ships, not shoes).” National Museums Liverpool. https://www.liverpoolmuseums.org.uk/stories/its-plimsoll-day-and-were-talking-about-ships-not-shoes