The change of government in 2010 provoked a large structural change in the English education landscape. Unexpectedly, the new government offered primary schools the chance to have 'the freedom and the power to take control of their own destiny', with better performing schools given a green light to convert to become an academy school on a fast track. In England, schools that become academies have more freedom over many ways in which they operate, including the curriculum, staff pay, the length of the school day and the shape of the academic year. However, the change to allow primary school academisation has been controversial. In this paper, we study the effect for the first primary schools that became academies. While the international literature provides growing evidence on the effects of school autonomy in a variety of contexts, little is known about the effects of autonomy on primary schools (which are typically much smaller than secondary schools) and in contexts where the school is not deemed to be failing or disadvantaged. The key finding is that schools did change their modes of operation after the exogenous policy change, but at the primary phase of schooling, academisation did not lead to improved pupil performance.