Abstract
This article provides a comprehensive analysis of the ideological evolution of the Conservative Party and the Labour Party of the United Kingdom concerning European integration over the period 1970–2016 and seeks to explain the causes of their diametrically opposed transformations. The methodology is grounded in general scientific principles of historicism, objectivity, scholarly rigour, and systematic analysis. The study employs civilisational, socio-historical, institutional, and micro-historical approaches. The source base comprises doctrinal party documents, speeches by leading political actors, statistical reports, public opinion data, and the results of referendums. The article’s original contribution lies in its analysis of the process of ideological evolution of the Conservative and Labour parties of the United Kingdom with respect to European integration from 1970 to 2016. It also characterises the key stages of this process, which led to a reversal of positions: from the pragmatic pro-Europeanism of the Conservatives and the radical Euroscepticism of the Labour Party in the 1970s to the deeply entrenched Euroscepticism of the former and the moderate pro-European stance of the latter on the eve of the 2016 referendum. Conclusions. The ideological evolution of the Conservative and Labour parties of the United Kingdom regarding European integration during 1970–2016 was shaped by two principal factors. First, the European issue was systematically instrumentalised to address domestic political challenges. Second, the evolution of the European Union from an economic to a political union elicited contrasting responses, alienating Conservatives while attracting Labour. Additionally, the article demonstrates that the consequences of this ideological evolution were markedly different for each party: for the Labour Party, the shift towards pro-European positions became an integral part of its modernisation and consolidation processes, whereas for the Conservatives, the deepening of Euroscepticism became a source of chronic internal division.