This article investigates the contingency plan developed by Harold Wilson’s Labour government for a ‘no’ vote in the UK’s 1975 referendum on European Community (EC) membership. The decision to prepare for the possibility of leaving the EC was seen as responsible, but the primary rationale for devising an EC exit strategy related to the severe political and economic damage that officials believed the UK would suffer if it withdrew from the Community. Officials emphasised the political consequences of a ‘no’ vote in part because the economic consequences were more difficult to predict and because of the rationale that underpinned the decision to join the EC in the first place. This was not easy to communicate in the politicised atmosphere caused by the divisions over the question of membership among ministers. In the end, the key message of the contingency plan was that leaving the Community would weaken the UK and leave the government with few options except “Going it Alone”.