The history of neoliberalism is a messy attempt to turn theory into practice. Neoliberals struggled with their plans to implement flagship policies of monetarism, fiscal prudence, and public sector privatisation. Yet, inflation was still cut, welfare slashed, and the public sector ‘marketised’. Existing literature often interprets this as neoliberalism ‘failing-forward’, achieving policy goals by whatever means necessary and at great social cost. Often overlooked in this narrative is how far actually existing neoliberalism strayed from the original designs of public choice theorists and neoliberal ideologues. By examining the history of the Thatcher government's public sector reforms, we demonstrate how neoliberal plans for marketisation ran aground, forcing neoliberal governments to turn to an approach of Managed Competition that owed more to practices of postwar planning born in Cold War US than neoliberal theory. Rather than impose a market-like transformation of the public sector, Managed Competition systematically empowered top managers and turned governance into a managerial process; two developments that ran directly against core precepts of neoliberalism. The history of these early failures and adjustments provides vital insights into the politics of managerial governance in the neoliberal era.