Animation in the UK has had a long history of being used by creators and funders as a form of communication, conveying concepts, ideas and messages to audiences in an entertaining format. Despite this long history, UK-produced animation has also had a parallel history as a form of socio-political intervention, where communicating concepts, ideas and messages has been practiced with the aim of both raising awareness of socio-political issues and injustices, and potentially prompting forms of activism. A small portion of this parallel history has been documented, most notably through past research into the history of animated propaganda and animated public information films of the 20th Century. However, relatively little is known about how a broader range of animated genres have worked as socio-political interventions or why they have been perceived to have had the potential to prompt activism. I used two independent approaches to identify how and why some UK animation has been used as socio-political intervention throughout the 20th and early 21st Centuries: an exploratory analysis and an emancipatory case study. Exploratory analysis consisted of a literature review to define five types of grassroots activism (class struggle, collective behaviour, social movements, new social movements, and advocacy) and thematic film analyses of key examples of animated films from animated documentary, propaganda, public information and advocacy genres, to identify correlations between the types of activism and the films. Emancipatory case study of the Leeds Animation Workshop consisted of in-depth interviews, film analyses and archival document analyses to determine how an activist animation production organisation successfully used animation for activism across a timespan of 40 years. This study revealed that four major processes were present across animation production, distribution and exhibition practices for animated documentaries, public information films, student-produced animated propaganda, and advocacy campaign films that demonstrated potential for facilitating the types of activism defined in the thesis. These processes were: the development of an emancipatory ethos, a democratised animation production practice (particularly for groups and collectives), the use of propaganda and polemics, and a supporting eco-system of mobilizing strategies and resources. An exception was identified with government-sponsored animated public information films, where film analyses revealed a more 'top-down' approach to the four major processes, which was reflected in the film narratives and persuasion techniques. These were apparent during times of national social and political upheaval. Interestingly, where grassroots animated films were funded by UK or EU governmental, institutional or highly bureaucratic departmental bodies, interviews I conducted supported by film analyses revealed that those sources of funding often presented, to emancipatory-minded filmmakers, the potential for creating films that could foster greater inclusion of progressive changes into social policy. Simultaneously, such potential also presented the possibility of filmmakers being co-opted due to closer interaction with those funding bodies, sanitising the politics and messaging of films in the process. The findings indicate that a range of filmmaker and commissioner assumptions about the efficacy of UK animated film tended to underpin and motivate the continued use of the various animation genres as activist interventions, particularly when combined with the four major processes mentioned above. The findings are synthesised into a theoretical model; an emancipatory media framework that illustrates the 'mechanics' of a model of animation as a means for activism. The study and the framework are relevant to individual animators and filmmaking collectives, activists using film, community and independent media initiatives, social capital projects, and those researching animation and activism in scholarly or practice-based ways. Further research on the user/audience reception of grassroots-oriented animated films via participatory action research with local communities would expand appropriately on this subject.