Political scientists (Evans and Menon, 2017: xiii) have argued that: ‘The Referendum, and the events that have followed it, can only be understood via a grasp both of the UK's relationship with the EU and of more general developments in British politics over the last few decades.’ The review in this book of the events leading up to the signing of the Treaty establishing the European Economic Community (EEC) in 1957 and its implementation would suggest that, in the social domain, a much longer time span is necessary to uncover the origins of the many factors explaining the Leave vote in the 2016 referendum. The Leave and Remain campaigns highlighted to differing degrees the loss of control over national social welfare systems and the encroachment of the European Commission and Court of Justice of the European Union (CJEU) in other areas of social policy. They both emphasised the threat posed to member states by migration. All of these issues can be traced back to the EEC Treaty.

The UK's membership of the European Communities/European Union (EC/EU) coincided with a period during which the notion of social Europe, or European social integration, progressively moved onto the agenda based on a broad set of shared social values, standards and objectives (Vandenbroucke, Barnard and De Baere, 2017: xix). By the time the UK triggered article 50 on 29 March 2017, EU soft and hard law spanned the whole panoply of social rights, enshrined in the 2000 Charter of Fundamental Rights of the European Union. The longstanding hostility of UK governments to EU intervention in national social affairs was reflected in public opinion. The level of contestation of European authority became more acute in the wake of the 2008 global financial and 2010 eurozone crises, as did open expressions of euroscepticism and disaffection with the European project among political parties and electorates across the EU.

During more than 40 years of EC/EU membership, successive UK governments pledged to give the public an opportunity to determine what relationship the UK should have with the EU (Westlake, 2017). Until 2016, only the Labour government of 1974−76 had fulfilled their commitment to hold a referendum on continuing membership of the EC/EU. In 1975, just two years after joining, the electorate voted for the status quo.