The nature of international trade has changed in the first decade of the 21st century. Many production processes have become organized in internationally dispersed supplier networks, so-called global value chains (GVCs). This tendency has implications for the competitiveness of countries and regions. This paper uses the regionalized world input-output tables from the EUREGIO-database, for 2000 and 2010. These give quantitative descriptions of the world production structure, and the linkages between regions and countries regarding the sourcing of raw materials, parts, components and (business) services. Linking regional data on employment by industry to these tables allows us to quantify differences in the extent to which UK regions were contributing to GVCs. It also presents indications of changes in regional competitiveness and numerical evidence on regional Brexit risks for regional employment.