Brexit and the emergence of a Transnational European Community of Practice: From grassroots mobilisations to supranational political opportunity structures in the struggle for citizens' rights

Brexit ignited an unprecedented sense of shared European identity and belonging, catalysing pro-EU social movements among EU nationals in the United Kingdom and amongst British citizens residing in the EU and leading to the formation of a transnational European community of practice. This mobilisation coalesced around grassroots organisations whose claim-making strategy was rooted in the institution of EU citizenship, which also grounded their legitimacy. Drawing on a relational approach to diasporic and transnational social movements, mixed methods empirical research including the findings of an online survey of mobile citizens (n = 1919), archival and documentary analysis, expert interviews and policy analysis, the article analyses the significance of supranational political opportunity structures to the emergence of a transnational European community of practice during Brexit and the formation of an alliance between two of the primary grassroots organisations advocating for citizens' rights – the3million and British in Europe.