Since the Brexit referendum of 2016 a number of studies have found that Boris Johnson’s decision to join the Vote Leave campaign was a decisive factor in the result. While respected commentators and politicians have claimed that his journalism played a role in shaping views on Europe, there is little literature to support this thesis. This study examines the role played by Johnson’s journalism on the shaping of elite opinion on the European Union within the Conservative Party, from the early 1990s until 2016. His writing is contextualised within the history of Conservative Party Euroscepticism. Drawing on over 30 years’ of Johnson’s journalism, first as the Telegraph’s Brussels Correspondent and later as an opinion columnist, the study uses a framing analysis to explore the major themes of his work. Using a critical elite theory perspective, which focuses on inter-elite communications to understand the role of the media in the policy process, Johnson’s journalism was then evaluated to determine its influence on Conservative party thinking on Europe. This dissertation argues that Johnson’s journalism deftly mined and amplified a number of British cultural pre-dispositions. The most significant was a deep distrust of any external jurisdiction that threatened British parliamentary power. The threat to sovereignty posed by the EU emerges as the major frame in Johnson’s work. The dissertation presents findings from interviews with leading diplomats, Conservative politicians and journalists which indicate that Conservative party opinion on Europe was influenced by articles that Johnson – and others – wrote. The findings indicate that Johnson had greater reach and influence owing to his platform in the Daily Telegraph, the Conservative Party’s “house journal”. Conservative backbenchers during the Maastricht period viewed Europe in part through the prism of Johnson’s lens. Secondly, Johnson specialised in a form of ‘Euromyth’ that trivialised the EU and painted it in an absurd light. This partly set the tone for coverage of Europe in other newspapers. This study presents evidence that Johnson, operating at elite sites, played a social and cultural role in shaping agendas on Europe within the Conservative Party.