This article explains the background to the investigation of MCR processes in South East England and the North West Europe POLYNET study. It reports on the policy challenges for the South East England MCR, revealed by transnational analysis. London - considered a monocentric spatial form in European policy - has emerged as the most functionally polycentric region studied. But, although European spatial guidance underpins policy frameworks for the MCR, major barriers to implementation are identified. Effective powers, finance and governance are found to be lacking at the MCR scale. More challenging, tensions between Europe-wide objectives - for balanced spatial development, growth and competitiveness - seem to compromise fundamental priorities for sustainable development. (A)