This paper constructs an original database on physical capital, labor, education, GDP, innovations, technology spillovers, and institutions to analyze the proximate determinants of British economic growth since 1270. Several approaches are taken in the paper to tackle endogeneity. We show that education has been the most important driver of income growth during the period 1270–2010, followed by knowledge stock and fixed capital, while institutions have not been robust determinants of growth. The contribution of education has been equally important before and after the first Industrial Revolution. Overall, the results give strong support to the predictions of Unified Growth Theories.