Following political devolution in the late 1990s and the establishment of the governments for Wales and Scotland, the education systems of the four home countries of the UK have significantly diverged. Consequently, not only does that mean that education research in the UK has to be sensitive to such divergence, but that the divergence of policy and practice provides an important opportunity to undertake comparative research within the UK. Such "home international" comparisons between the four home countries of the UK also provide the opportunity to undertake "natural experiments" of education policy and practice across similar socio-economic contexts. By drawing specifically on the UK Millennium Cohort Study (MCS)--a recent longitudinal birth cohort study specifically designed to provide the potential for geographical analysis--the paper finds considerable variation in child development by country of the UK, with no single story of "success." However, the paper finds that literacy development amongst children in England is, particularly in London, on average, greater than for children elsewhere. The paper concludes by arguing that "home international" comparisons must take seriously issues of scale and geography when interpreting the influence of "national" education systems and policies on educational outcomes.