Subnational migration in the United Kingdom: producing a consistent time series using a combination of available data and estimates

There is no single framework in place in the United Kingdom for collating and harmonizing the data on migration taking place between the subnational administrative units that constitute the home nations, together with the flows of international migration between these areas and the 'rest of the world'. This paper proposes the construction of complete matrices of subnational migration statistics on an annual basis which can then be used to monitor migration trends throughout the UK in a comprehensive manner. The paper reviews how various 'known' flows are estimated by the national statistics agencies and develops estimates to fill in the gaps in the matrices. It then looks at changing patterns of migration in the UK between 2001/2002 and 2010/2011, showing that migration exhibits most activity in the middle of the decade. Flows within the home nations are the most consistent over time, while the patterns of international migration and migration across the borders of the home nations exhibit more substantial change. The latter flows, although relatively small in magnitude, have not previously been studied at the subnational level in any detail. Patterns of subnational internal and international net migration are found to be negatively correlated.