This introductory chapter provides a brief overview of government and party positions towards European integration up to the 2016 referendum on the United Kingdom’s membership of the European Union. It then assesses the existing historical and political science literature and the ways in which this has investigated and made arguments related to British party policy and public opinion towards European integration. Through analysing existing works, it is argued that this book provides a challenge to many accounts that place an emphasis on Britain being a reluctant participant in European integration. However, this more positive portrayal of the political class’s commitment and attitude towards Europe is countered by the book’s findings related to British public opinion. The chapter proceeds to introduce the sources and methods used in the book, providing a detailed discussion about the challenges of analysing historical public opinion data. It concludes with an overview of the structure of the remaining chapters.