This paper advances the study of microblogging and political events by investigating how one high-profile broadcast acted as a stimulus to real-time commentary from viewers using Twitter. Our case study is a controversial, high-ratings episode of BBC Question Time, the weekly British political debate show, in October 2009, in which Nick Griffin, leader of the far-right British National Party, appeared as a panelist. The "viewertariat" emerging around such a political event affords the opportunity to explore interaction across media formats. We examine both the structural elements of engagement online and the expressions of collective identity expressed in tweets. Although many concerns noted in previous studies of online political engagement remain (inequality in the propensity to comment, coarseness of tone), we find certain notable characteristics in the sample, especially a direct link between the quantity of tweets and events on the screen, an ability to preempt the arguments offered by panelists, and ways in which viewertariat members add new content to the discussion. Furthermore, Twitter users commenting online express a range of overlapping identities. These complexities challenge broadcasting and political institutions seeking to integrate new, more organic models of engagement.
