The Qualitative Election Study of Britain (QESB) is the first (and only) qualitative longitudinal dataset to investigate political attitudes and voting behaviour over multiple elections and referendums in the United Kingdom. During the 2015 UK general election over 90 voters participated in 23 focus groups across England, Scotland, and Wales before and after polling day. These participants represented a range of political party supporters and independent voters, age groups, and economic backgrounds. They discussed a range of political issues including their vote choice in the election, their impressions of the major party leaders, why they would consider voting (or never voting) for a political party, and their expectations for the country moving forward. Special focus groups were also held around the three leaders' debates. The 2015 QESB also brought back participants who had participated in the 2010 QESB focus groups and the 2014 Scottish referendum focus groups. The 2015 QESB has created a unique panel of participants whose political opinions can be tracked across multiple elections. The project also includes questions that were asked in prior election focus groups and has replicated, with some modifications, the research design of the previous wave of the study.