Abstract
Jeremy Corbyn's election as Labour leader in September 2015 brought a surge of new members and a reputation for an unusually energetic, and unusually combative, online following. I test what changed in the place where that following met the party most directly: the comment section of Labour's own Facebook page. I compare every comment that could be retrieved from posts on the page between 1 January and 12 April in 2015, under Ed Miliband (174,560 comments on 461 posts), and in the same weeks of 2016, under Corbyn (60,019 comments on 131 posts). I score each comment with an open toxicity classifier, track who and what it mentions, follow the 1,964 accounts that commented in both years, and read a random sample of 300 comments with AI assistance to estimate stance. In the same weeks of the year, the comment section under Corbyn was smaller, more conversational and slightly less toxic: 8.9% of comments were toxic in 2016 against 10.9% in 2015. About half of that fall reflects a change of crowd: the accounts seen only in the 2015 window had been more toxic than those seen only in 2016. The other half is a smaller fall among the accounts that commented in both years, which is shared with the rest of the page and may reflect the period rather than the people. What changed most was the argument: comments about UKIP fell from 9.6% to 3.0%, and comments about the EU, the leader and Labour's internal factions rose. Comments the classifier flagged as identity attacks and that mentioned Jewish people rose from 12 to 18. On reading, most in 2016 accused Labour of tolerating antisemitism or challenged other commenters, but the numbers are too small, and the classifier too unreliable, to estimate how common antisemitic comments were. The comparison is descriptive: two periods on one page cannot separate the effect of a leader from the effect of an election year, and comments from 2015 were retrieved a year after they were written and fewer of them survived. Within those limits, the evidence suggests that this comment section, in these weeks, did not become more hostile under Corbyn, and that the main change was in what people argued about. Files: the preprint (PDF); weekly counts of comments and of toxic, insulting, obscene, identity-attack and threat comments as classified by Detoxify; and topic shares by year. No comment text, commenter identifier or post identifier is included. Provenance and AI use. The data were collected with Netvizz for my doctoral research, before Netvizz closed in 2019. This paper builds on my doctoral thesis (Hotham 2021, University of Bath). The analysis and writing were completed in 2026. The analysis code and drafts of the text were prepared with the assistance of an AI system (Claude, by Anthropic), which was also used to review drafts. I checked the analysis and the text and take responsibility for both. Version 2 added this statement to the paper, and version 3 changes only the date on the title page; the findings are unchanged. Version 4 (October 2026) corrects the word list for mentions of the Conservatives, which had counted any use of "hunt" (including Tristram Hunt, a Labour MP, and phrases such as "witch hunt"); it now counts only Jeremy Hunt. Mentions of the Conservatives in 2016 change from 20.0% to 19.8% of comments, the word list in the appendix now matches the code, and the topic shares file is corrected to match. No other reported figure changes.
Cite
Hotham, T. (2026). New Leader, New Crowd: Labour's Facebook Comment Section from Miliband to Corbyn. Preprint, Zenodo. https://doi.org/10.5281/zenodo.23298975